Suggestions for further reading and information on the secondary literature, on which this presentation is based, are found concentrated at the end of these remarks. In regards to quotations from primary sources offered here, it was attempted to access their translations available on the Internet.
For an account of the processes that ultimately led to a differentiation between nascent Judaism and Christianity, it is essential to take into view the very differing perspectives the actors and observers had at the time. The view of things change significantly, depending on whether the sources that the researchers used, are texts by Jewish followers of Jesus, or those of Jews, with no reference to Jesus of Nazareth, of non-Jewish members or sympathizers of the Jesus movement, of people within or outside of Judea or Galilee, or non-Jews with no reference to the Jesus movement.
In addition, those texts -- the New Testament, the writings of the Church Fathers, the deuterocanonical literature, the early rabbinic works, letters, philosophical treatises, etc. ¬– can convey only a fragmentary picture of the exciting centuries in which Judaism and Christianity unfolded in mutual demarcation from each other. Anything that the science on this issue can say, is, therefore, hypothetical and provisional.
2 Traditional models of demarcation between Judaism and Christianity
2.1 Traditional Jewish perspectives
To those rabbinical scholars,  who from the 2nd century on formed themselves as marginal group within nascent Rabbinical Judaism, nascent Christianity presented itself not as a unified group. They were not interested in the views of non-Jewish ("Gentile Christian”) followers of Jesus, but clearly in the convictions of the Jewish ("Jewish-Christian") members of the party of the Nazarene.
Whatever the "Gentiles" believed or thought was in the eyes of the rabbis completely their affair; their cults and religions did not fall within the remit of rabbinical jurisdiction as "Avodah Zarah" (i.e. foreign worship or idolatry). Non-Jews were not part of Israel, and therefore exempt from obligation to the Torah. But whatever Jewish followers of Jesus believed or did, was of immediate concern to the scholars. They were of the opinion that the Nazarenes were a form of deviation (“Minut”) from the path of the commandments that had been mediated by Moses. "Minim" (followers of a Minut) included not only the "Jewish Christians,” but also Jewish Gnostics, who denied the identity of God as creator and as redeemer.
While the early rabbinic scholars showed a kind of indifferent tolerance towards "Gentile Christians,” they advised their people to avoid close contact with the Jewish followers of Jesus. The followers of Jesus should not be given the opportunity to spread their teachings among Jews.
In the eyes of the rabbis, their own interpretation and actualization of the commandments of the Torah, as it was first compiled in the Mishna (at the end of the 2nd century), was the sole legitimate continuation of the traditions of Ancient Israel .
The way in which the rabbis perceived the nascent Christian church, was transformed, however, in later centuries, probably under the influence of the reign of Constantine and his successors. The Babylonian Talmud (6th/7th century) may represent (may have represented) much more aggressive forms of rabbinic discussions with "Christians.” Though the exact extent is difficult to determine in detail, because the literary form of Talmudic polemics does most of the time not lend itself to the identification of unique instances. In addition, the Talmud was in the Middle Ages subjected to intense censorship, which was directed especially against it’s supposedly anti-Christian statements.
A typical example of the polemics of the Babylonian Talmud against early Christian teachings, in this case with indirect reference to Mt 5:13, is provided by bBekhorot 8b. Rabbi Jehoshu'a ben Hananiah goes to the Athenaeum [in Rome] purporting to learn from its sages. There ensues a kind of contest, in which the sages submit certain tasks and trick questions to the rabbi, which Jehoshu'a always parries sovereignly.
They [non-Jewish sages] said to him [Rabbi Jehoshu’a]: Tell us a fictional story! He said to them: There was the mule that had given birth. It had a piece of paper around its neck, on which was written: There is a claim against my father's house [in the amount of] a hundred thousand Zuz. They said to him, How then should a mule give birth? He said to them: This is but a fictional story! [They asked him:] salt, which has become weak -- wherewith shall it be salted? He said to them: With the afterbirth of a mule. [They asked,] Does a mule have an afterbirth?! And salt, can it become weak?! (bBekhorot 8b)
Of course one could take the little dialogue as that which is obvious: A competition of smart reactions to absurd suggestions. The image of the salt that has lost its savour and is good only for casting it out and to be trodden under foot (Mt 5:13), but it is rather more concise. After all, it was mostly used as symbol for the "old" people of the covenant, Israel. It was supposed to have become "weak" and was, therefore, replaced by the new "salt of the earth.” The Talmud now asks (with some justification): How does that work? Can the salt (the Old Covenant) lose its power? Sure, is the snappy answer: People who believe in the ability of a mule to give birth could also believe the desalination of salt. Yet, even more sardonic sounds the passage, if we assume (for which there is some evidence)  that the unexpectedly fertile animal stands as a cipher for the virgin, who is humanly not fit to give birth to children. People who are fooled by absurd fictional stories cannot be helped!
2.2 Traditional Christian Perspectives
The question of who could be considered to be the rightful interpreters of the traditions of ancient Israel, was for the early "Christian" authors as clear, as it was for the rabbis: Nascent Christianity declared itself to be the only legitimate heir to the Hebrew Bible. This Christianity was the "New Israel;” it was, as a partner in the "New Covenant,” associated with the God of Israel and had displaced the Jewish people, the “old Israel,” from its unique relationship with the Eternal One.
The law, given at mount Horeb is already outdated and belongs to you alone, but ours applies generally to all people. If a law is arrayed against another, it abrogates the earlier one and in the same way a later covenant erases the earlier one. Christ is given to us as an eternal and final law, and we can rely on the covenant, which is not followed by any law, regulation or commandment. [ ... ] The true, spiritual Israel, namely, and the descendants of Judah, Jacob, Isaac and Abraham, who, in spite of his foreskin, as a result of his faith, received his testimony from God, was blessed by him and appointed to be the father of many nations, which we are, we were guided through this crucified Christ to God, as is to be seen in the course of further conversation. 
This theological concept is in the research referred to as "substitution theory.” Basically, this view of things dominated both, Christian theology as well as the theologically inspired religion-historical perspective into the seventies of the 20th century.
As in the rabbinic view, there exists, in a sense, a direct line from the Torah of Moses to the Mishnah and the Talmud, so the nascent church saw itself in complete continuity with "Moses;" Judaism, interpreted as having survived, was represented by contrast as a "heresy.”
2.3 Traditional Gentile ("pagan”) perspectives
Many Gentile outside observers, such as the philosopher Celsus, (end of the 2nd century), completely failed any understanding of these boisterous processes of demarcation between "Jews" and "Christians.” If any differences were perceived between the two (which was by no means always the case), then it was the development of Christianity that presented itself as a strangely twisted Judaism. Usually one took both communities as a conglomerate of an oriental cult, which was perceived either as (syncretistically) attractive or as dangerous or absurd.
Let us now consider what he has to say to those, who have become believers from among the Jews. He claims, "that they, seduced by Jesus, had left the law which they had inherited from their fathers, and had been cheated in a ridiculous manner to cross over to another name and another life." Whereby he did not even consider that these Jews who converted to Jesus, did not at all leave the law, they had inherited from their fathers.” Because they live according to its rules and have also received their name from the poverty of the law, which is experienced if one understands the law. [ ... ] If Celsus had known all this, he would not have his Jew speak these words "to the converted from among Judaism: "What has happened to you, citizens, that you have forsaken the law inherited from the fathers and from the things we have just conversed about, to be enticed and cheated in a ridiculous manner away from us to another name and another life? 
It turns out that the contemporary authors each publicized their own view on the development of the two groups that, as a rule, not distinguished itself by sensitivity and ‘objectivity.’ A major difference between the rabbis and their 'Christian' counterparts was that, in principle, the former had no interest in non-Jewish followers of Jesus: Whatever the Gentiles believed and practiced, was entirely their own affair. Non-Jews were not proselytized. Nascent Christianity, however, behaved quite differently. It developed into a universal current that wanted to reach and convert everyone (all humanity).
For late antiquity, this setting the course implied nothing less than a revolution. Before the universal orientation of nascent Christianity, there were essentially two types of religions (better: cults). For one, the gods were attended to, or worshipped, in the traditional framework of their own ethnic group, one’s own town or one’s culture.  One was thus born into a ‘religion’ that one practiced because of family ties and the socio-political loyalty to one’s living environment. On the other hand, there were several national ‘religions,' such as the so-called mystery cults (e.g. the Mithras or Isis cult). These cults one could, according to personal inclination, as it were, privately, add to the native public ‘religion.’ As a result, numerous syncretisms emerged -- mixed forms and mergers of regional and national cults or individual combinations of private and public religious practice .
In contrast to ‘Judaism,’ which as ethnically oriented 'religion' almost seamlessly fitted into the late antiquity context, the development of Christianity broke with many of these centuries-old conventions: It just did not want to fit into any ethnic boundaries, it refused any syncretism and took for itself the ‘Jewish' privileges, not to participate in the usual cult around the ruler. In order to understand the partially harsh reactions of the environment on this newly emerging ‘cult', it must be borne in mind that the developing Christianity in fact put in question each one of the proven and old conventions of cultic socialization. 
2.4 Digression: Paul
How did it happen? How could a small group of Jewish followers of Jesus develop into a universal missionary current? A first switch setting, which ultimately led to the revolution described, took place quite early. One can see it already in the theological concepts of [the apostle] Paul (he died about the year 65) to whom Christianity owes the oldest comments on the ministry of Jesus.
In the following, an attempt is made, almost in telegram style, to develop a view of the oldest author of the New Testament, who deliberately situates it in the context of the described ‘cultic revolution.' In parts of New Testament scholarship, the view has prevailed, to describe Paul as a Jewish thinker. As we will see, this perspective can actually help to better understand his concern and his activities.
Paul, who’s name in the Jewish tradition was Sha'ul (Saul), was born into a Greek-speaking family in Tarsus. It seems that he had undergone a thorough Jewish education. He knew the Bible, understood Jewish interpretation techniques and also mastered the Hebrew language. In one of his autobiographical testimonies (Gal. 1:13-14), he describes himself as a traditionalist and radical zealot for the Torah, who persecuted the early Jesus movement because he considered it to be dangerous.
At a certain time he experienced a vision of the risen Christ (1 Cor. 15:8 - 9 ). This event would become the ultimate turning point in his life. For Paul, the traditionally educated Jew, the certainty that Jesus of Nazareth had been raised from the dead, could mean only one thing: The end-time had come, the resurrection of all the dead and the Last Judgment was imminent.
Now it was the time to respond. A number of prophetic texts of the Bible assume that "in the last days" the nations of the world will give up their rejection of the God of Israel and go on a pilgrimage to Zion:
At the end of days it will happen: Established is the mountain of the house of the Eternal, as the highest mountain he towers over the hills. There flock to him all nations. There go many nations and say: Come, let us go up to the mountain of the Eternal, to the house of the God of Jacob. He will teach us His ways, on His paths we want to walk. For out of Zion comes instruction [Torah] and the word of the Eternal from Jerusalem. He judges among the peoples, corrects many nations. Then they will hammer their swords into ploughshares, and their spears into pruning hooks. No people rises sword anymore against people. And one does no longer learn war. (Isaiah 2:2-4)
For Paul (as well as for other Jewish thinkers at other times) it was clear that the advent of the end-time meant that a paradigm shift in the behavior towards the non-Jews (Gentiles) had to happen: They had now as soon as possible to be converted to the God of Israel, so that the old aeon would come to an end as soon as possible, and the eschatological kingdom of peace would dawn. This explains the feverish haste, in which Paul hurried from city to city in order to bring "his Gospel,” his version of the Gospel, which concerned the fact that one human had been resurrected from death, to as many Gentiles as possible:
I remind you then, brethren, of the good news [the Evangel, the Gospel] which I have proclaimed to you that you have received [ ... ]: I have first narrated that which I also received: that Christ died for our sins according to the scriptures, and that he was buried, and that he was raised on the third day according to the scriptures, and that he was seen of Cephas, then of the twelve. (1 Cor. 15:1.3-5 )
For Paul, it was quite unimportant, how exactly Jesus had lived or what he had taught. The key for him was the fact that a person had lived (sinless) and had indeed died (after all, he had been buried), and that this same human was resurrected (after all, he was seen by Cephas/Peter, and many others, including, among them as a last one also by Paul). Thus, without any doubt, the end-time had dawned.
The usual way to convert Gentiles to the God of Israel required careful instruction in the Jewish tradition, then men had to undergo circumcision. This same procedure was also propagated by (almost) all other apostles of the early Jesus movement, who, like Paul, felt that the end-time had now come, in which now all Gentiles must be brought to Zion.
Paul was in sharp disagreement. For him the time was so urgent that he, as it were, proposed a simplified procedure for the Gentiles for entrance into the "old" (!) people of God. The theological construction to explain this “Emergency Entrance" is referred to as the doctrine of justification. According to Paul, both Jews (by the commandments of the Torah), and Gentiles (through the well-ordered creation) had knowledge of the will of the Eternal. But those who ignored these or would not meet them, would incur the death penalty in the final judgment. Jesus had now -- in spite of his sinless life -- suffered death on the cross. This could only be explained in such a way that he had taken this punishment of death, so to speak, voluntarily and on behalf of all others upon himself (“substitutional atoning death"). Paul was convinced that non-Jews could now in faith rely on this already anticipated judgement of death by the death of Jesus. Gentiles would have to document this by baptism, which would make them through the Holy Spirit a "new creation" and thereby the commandments of the Torah would be fulfilled. In this way, the Gentiles would, without lengthy instruction and circumcision, become members of the people of Israel.
By the way, for Jews, this method was not enacted. They were already part of God's people and believed already in the Eternal One of Israel. They were also already committed by circumcision to the observance of the commandments of the Torah. However, Paul was never tired of emphasizing that access to Israel through baptism by no means implied a “second class” membership. No one, neither Jew nor Gentile, would qua ethnicity, because of his circumcision or because of his uncircumcision have any preference over the other .
The universalism of the nascent Christianity then was due to the belief that through the resurrection of Jesus the end-time had come, and that now anyone had to be converted to the One God (of Israel). This exceptional path for the Gentiles successfully propagated by Paul, whose complicated theological justification was, by the way, not really understood already in the generation after him, led to great missionary success of the nascent Christianity just among non-Jews. In some ("Gentile Christian" dominated) communities the exclusion of instruction and circumcision had, in the long run, the side effect that Gentiles were increasingly alienated from the Jewish tradition, respectively never learned anything about it.
3 Scientific perspectives
When one now turns to the scientific models that have been created to describe the development of early Judaism and nascent Christianity, one experiences first the startling observation that these concepts are highly dependent on the prevailing theological terms of reference. The "objectivity" of science falls short of its claims -- which is not only true for theology. Actually, the opposite would also be surprising: If it were possible for researchers to keep in their judgment completely independent of the paradigms of their own respective social contexts.
3.1 Early Judaism as "late Judaism" -- a disguised Doctrine of Substitution
Into the seventies of the 20th century (and with some Christian scholars even beyond), a majority of scientists imported the substitution theory into their representations of the processes of the first and second centuries. Particularly revealing is the term "late Judaism,” which was actually used for the nascent Rabbinic Judaism of the first century(!).
This term is based on the conviction that the development of the 'religion' of Ancient Israel took place in several stages, so to speak, and consistently towards Jesus of Nazareth. After the "religion of Moses,” represented by the Torah, followed -- according to this model -- the "religion of the prophets." This was supposed to have represented a significant progress over the Mosaic stage of development, with its more archaic retaliation mechanisms. The new approaches of the ”time between the testaments of the Bible,” were apocalyptic concepts and with them appeared the idea of resurrection and of life after death, followed by the time of Jesus and, in parallel, what they called, "late Judaism."
The term “late Judaism” implies to have to deal with a dying phenomenon, which had actually already outlived itself -- precisely because of the simultaneous appearance of Jesus. Amazing is only that those authors, who still used this term in the 20th century, had, in the meantime, to deal with nearly two millennia of this “late Judaism”!
3.2 "Parting of The Ways" -- The model of the "separate ways"
Towards the end of the 20th century, the stages model described above was replaced by the conviction, Judaism and Christianity had, at a certain time in their development, simply “gone separate ways.” It was, as a matter of principle, always assumed that Christianity would have separated itself from the existing ‘Judaism.’ The mutual relationship could therefore be described as mother- daughter-religions. 
The beginning points of separation were, however, dated quite diverse. Some have already seen them in Jesus of Nazareth, the supposed "founder of Christianity" because he had not taken the observance of some commandments seriously and had also shown a more open-minded attitude towards Gentiles. Others chose Paul as the “founder of the Christian religion,” arguing that Jesus had lived as a Jew and had died a Jew; at his death no shift towards Gentiles was to be seen. The apostle from Tarsus, however, had driven a deep wedge between the followers of Jesus and the Jewish people by his ‘mission without circumcision’ to the Gentiles.
Others again date the separation much later. The destruction of Jerusalem and the Temple in the wake of the great Jewish Revolt (66-70) would have to be the cause for the parting of the ways. For both communities a profound reorientation would have been required, which would ultimately have generated significant differences between the two communities. Perhaps, however, the ‘parting of the ways' has to be assessed even later -- about the time of the Bar Kochba revolt (132-135). After all, Justin Martyr (ca. 100-165 ) reports in his Apology (I,31) that Jews had persecuted Christians, because they had chosen not to participate in the Bar Kochba rebellion. However, an invitation to join the fight would only have been useful, if a separation between the two had not yet come to pass ...
3.3 "Wave Theory" - or: Everything is a little more complex
On closer inspection, the problems of such a "parting of the ways" are quickly revealed: Complex and diffuse structures such as (religious) currents, composed of many groups in different regions, are not roads that at times may bifurcate. Any kind of ‘parting of the ways' presupposes, however, that in the case of ’Judaism’ and 'Christianity' we deal with homogeneous entities.
Furthermore, it is problematic that too often science bases its mental models on a modern concept of religion (in the sense of "confession”), which can, however, not be transferred to conditions of late antiquity. The 'cults' of the first centuries fulfilled a number of public functions that were, for good reasons, withdrawn from the ‘religions’ of Europe after the confessional wars of the 16th and 17th centuries. They were by no means associations marked by theoretical teaching (theologies), who had to care for the spiritual needs of their members.
So it is quite implausible, to hold the doctrine of a particular scholar, for example, the North African theologian Tertullian (c. 150-220), for especially representative of his time. No one is able to say exactly whether and, if so, how much the traditional writings of authors of late antiquity reached the general population. After all, the vast majority of people could not read or write; manuscripts were mostly expensive and therefore limited in their circulation. Sermons, public oratory and debate, as well as orally transmitted tales have, most certainly, left a far greater impression on contemporaries -- unfortunately, these were in retrospect rarely written down.
Anyone who tries to reconstruct the beginnings of Judaism and Christianity on the basis of the handed down texts, has to be careful: It is quite possible that some statements which appear to be representative due to the currently available image area of a text, it may not actually be representative. The consequence can only be, to consider all processes to be more complex and diffuse than they appear at first glance.
The current research is trying to meet this concern by considering the boundaries between the two nascent ‘religions’ as being permeable.  Impulses and innovations, such as Platonic concepts or magical techniques, were taken from the environment of the time and processed in parallel. Likewise, the two influenced each other constantly; the processes of demarcation were taking place osmotically rather than hermetical.
Daniel Boyarin, one of the exponents of this paradigm shift, has proposed “to think of the Judaism and the Christianity of the second and third centuries as marking points on a scale”  between the complete rejection of the Hebrew Bible (and with it the common root of Jews and Christians) by the Marcionites, up to the complete rejection of Jesus by some Jewish groups. Between these two extremes, however, there were many intermediate stages, in which the degree of mutual delimitation was far less clear. This perspective Boyarin describes -- with recourse to linguistic theories -- as Wave-Theory.
From the basic assumption of a wide range of more or less interfering Judeo-Christian currents, results, on the one hand, that much longer development and segregation processes are to be expected, than older perspectives suggested. On the other hand, it may also have to be assumed that the expression of distinctly ‘Jewish' and 'Christian' identities took place in the various settlement areas and cultures in their own ways and at different times.
A good example for the complexity of these processes is Antioch. As one of the largest cities of the Roman Empire, the city had both, vital Jewish, as well as a significant Christian communities. John Chrysostom (344/349-407) — (the Greek epithet given to him was the “golden mouth,” because of his extraordinary rhetorical skills) — worked in Antioch from about 381 to 397. In the history of Jewish-Christian relations he is one of those, who in his sermons applied himself to violent and truly nasty invectives against the Jewish people. His problem was in fact that his "Christian" congregation, the listeners to his sermons, found nothing wrong with attending the synagogue on the Sabbath and the church on Sunday. They celebrated Jewish and Christian festivals alike -- because they did not perceive the ‘borderline’ between the two communities as exclusive. Much to the annoyance of their preacher Chrysostom.
4 Reconstruction: The long road to personal identity
However, the complexity of a process does not need to prevent anyone from trying to present the protracted search for a Christian identity. In this case too, only a rough sketch is possible within the framework of an essay.
The Jewish people (and among them certain followers of Jesus) experienced the first centuries as characterized by serious military catastrophies. After decades of civil war, the Holy Land was shaken by the Great Jewish Revolt from 66 to 70 (73 ), which for all residents, irrespective of their ethnicity and cultic affiliation, had a tremendous impact. Again, from 132 to 135 raged a bloody war in the country. This time the fighting took place probably in a smaller space, but certainly no less fierce. In the following years it came to massive restrictions in the entire empire by the Romans against the Jewish people, for example, by burdening them with a special tax, the fiscus iudaicus.
In the years between the two anti-Roman uprisings in the Holy Land (about 114-117) Jewish communities in the Diaspora rebelled, so in Egypt and Cyrenaica, Cyprus, and possibly in Babylon (Mesopotamia). As a result, the once flowering and significant Jewish communities (such as in Alexandria) ceased to exist; some of them for a very long time.
In the environment of Palestine Jewish life experienced severe impairments. It seems that many Jews tried, in the decades after the riots, to survive by adapting themselves as much as possible to the prevailing culture. At least archaeological findings suggest that in the late 2nd century it came to a massive shift away from the "paternal traditions" in many Jewish towns of Palestine. A small number of scholars, however, endeavored to teach and to update these same "paternal traditions" and to live them in everyday life. From these marginal, informally organized groups, developed the so-called “Rabbinic Judaism” that gained increasing influence and from about the 6th century would take over the leadership of the Jewish people.
At the same time prospered Jewish communities in other parts of the Empire. Also (increasingly), ‘Gentile-Christian' communities outside of Palestine gained in importance, despite sporadic local persecutions. It is reasonable to assume that the rabbinic reading of the ”paternal traditions," which should really have minted "classical Judaism," was unknown or had no significant effect in Jewish communities of large parts of the Roman Empire.
4.1 The "Constantinian shift"
The political reforms of Emperor Constantine (272/3-337) resulted in an (added) attempt to enhance the unity of the empire that was drifting apart, through introducing cultic reforms. In 313 he and his co-emperor Licinius promulgated the "Milan's Agreement,” which granted permission to the inhabitants of the empire -- among them explicitly Christians -- to attach themselves to a ‘religio’ of their choice. The advancement of Christianity as "state religion" was thereby not implied, even though Constantine specifically promoted Christian institutions and persons in the following years.
The significant consequences that resulted from the Constantinian reforms for the development of Christianity, are sufficiently well known. In the following, therefore, the concern will be, what impact this had on the nascent Rabbinic Judaism and their mutual relationship.
The privileging of Christianity first brought with it no real deterioration of Jewish concerns; it came -- on the contrary -- first to an upsurge in Jewish life, especially in Palestine. The reforms of Constantine included, among others, the strengthening of cultural self-administration, of which was made considerable use. Presumably it was (only now) that those institutions that, in classical literature, were brought in relation with the beginnings of the rabbinic movement, that a representative (Nassi) of Palestinian Jewry, who is -- a bit unfortunately -- usually named “Patriarch" lead to the beginnings of rabbinical jurisprudence and an (whatever kind of) educational system.
On the other hand, the reign of Constantine also launched a paradoxical development. In it’s course Palestine became ever more the heart of Christian interest. Up to that time the Holy Land had played a surprisingly small role in the development of Christianity. After the demise of the ‘early church' in the early 70s, the demographic and ideological centers of Christian life were consistently outside of Palestine. Little attention was given to the sites of the historical Jesus after 135. Constantine's mother Helena (248/50-330) brought about a fundamental change by her visit to the Holy Land. According to legend, she had found the cross of Christ at the site of the later Church of the Holy Sepulchre. The Church of the Nativity in Bethlehem and a building on the Mount of Olives go back to her initiative as well.
These activities led to a significantly increase in the Christian presence in the Holy Land. Pilgrims traveled there to visit the sites of the Patriarchs and Prophets (!); some of them settled there permanently. Other churches were built -- such as the magnificent St. Mary's Church ("Nea") built by Emperor Justinian I (482-565) in the Cardo of Jerusalem. All this led to the fact that the Jewish population of the Holy Land saw itself faced, in a paradoxical way, with their own traditions: The predominantly Gentile followers of Jesus provoked Biblical stories, went to the graves of Abraham, Isaac and Jacob, claiming at the same time that "the Jews" would misunderstand their own centuries-long heritage, because Jews were not able to find any references to Jesus in their Bible.
These factors, the recovery of Jewish self-administration favored by the Constantinian reforms and the significantly increased Christian presence in the Holy Land, led. within the Jewish population of Palestine, to a return to their own traditions. This development manifested itself in a significant increase in the construction of synagogues in Galilee, which effectively run parallel to the building of churches. On the other hand, the production of rabbinic writings (at least of those that have survived to this day) took a clear upswing in the 4th and 5th centuries. Texts were written to update the Bible (Midrashim) and also an important commentary on the Mishnah (the Palestinian and the Jerusalem Talmud).
4.2 The era after Constantine
The process of the forced self-definition of Judaism, which defined ‘Judaism' as a special group within the Empire and discriminated against it in the era after Constantine through numerous edicts and laws of now mostly Christian emperors. Fifty(!) laws were promulgated in reference to Jews between 337 (the death of Constantine) and 408/423 (the death of Arcadius/Honorius). Especially after the year 380 Judaism came successively under legal pressure: Laws that banned conversions were enacted, the possession of Christian slaves was forbidden to Jews, Christians were forbidden mixed marriages with Jews (388). Regional prohibitions of Jewish practices (Purim) are recorded from the early 5th century. In 418/425 Jews were excluded from imperial service. The repeal of the "patriarchy,” decreed around the year 429, ended the cultic self-government that Constantine had introduced.
Paradoxically, the Constantinian shift, therefore, favored the self-discovery of the two "siblings,” nascent Christianity and nascent Judaism. Through the development of Christianity as state religion, Judaism became more aware of itself in a twofold way: In the wake of the growing presence of Christianity in Palestine, its Jewish population came to witness a highly idiosyncratic use of their traditions by Christians. However, the growing legal discrimination against Jews after 380, led Jews only to increased reflection and group formation.
The exceptionally vital Judaism in many places, caused the Church Fathers some headache and nasty invectives against Jews (see Melito of Sardis, or Chrysostom, mentioned before). Judaism, which was supposed to have been replaced by the new people of God, the church, prospered happily ever after or even again. The substitution doctrine of the church, a theological construct, could not be brought into line with the historical reality of Judaism and would, therefore, again and again be taken as occasion for intense Christian attacks on Judaism.
- Daniel Boyarin, Abgrenzungen. Die Aufspaltung des Judäo-Christentums, ANTZ 10, Berlin, Dortmund 2009. [The Spilitting-up (or Fission) of Judeo-Christianity]
- Paula Fredriksen, Oded Irshai, Christianity and Anti-Judaism in Late Antiquity: Polemics and Policies, from the Second to the Seventh centuries, In: Steven T. Katz (Hg.) The Cambridge History of Judaism, Volume 4: The Late Roman-Rabbinic Period, Cambridge 2006, S. 977-1035; cf. http://www.bu.edu/religion/files/pdf/Christianity-and-Anti-Judaism-in-Late-Antiquity-Polemics-and-Policies-from-the-Second-to-the-Seventh-Centuries.pdf
- John Gager, Reinventing Paul, Oxford u.a. 2002.
- Peter Schäfer, Jesus im Talmud, Tübingen 2007.
- Seth Schwartz, Imperialism and Jewish Society:200 B.C.E. to 640 C.E., Princeton 2004.
- Guy Stroumsa, The Christian Hermeneutical Revolution and its Double Helix," in: Pieter W. van der Horst u.a. (Prod.), The Use of Sacred Books in the Ancient World, Leuven 1998, S. 9-28. Vgl. http://pluto.huji.ac.il/~stroumsa/Helix.pdf