Syriac Christianity originated and developed in areas in which communities of Diaspora Judaism existed. Throughout their history Syr. Christians lived in proximity to Jews, both in the cities of Syria and in North and Central Mesopotamia, and they shared with Jews their language and much of their religious worldview. The interactions between Syr. Christians and Jews can be studied on three different levels: 1. the common religious and cultural heritage, and the influx of ideas from Judaism into Syr. Christianity, in particular in the early period; 2. the literary representations of Judaism within Syr. Christian literature, which are often of a polemical nature; 3. the more occasional and incidental comments on contacts and exchanges between Syr. Christians and Jews in daily life. While Jews and Judaism are frequently mentioned and discussed in Syr. sources, explicit references to Syr. Christians are almost completely lacking from Jewish sources. Whether and to what extent certain passages in Rabbinic literature were written in response to arguments brought forward by Syr. Christians remains a question of scholarly debate. Evidence of Jewish interest in Syr. Christianity is occasionally found in the Middle Ages, e.g., when R. Hai Gaon (939–1038) expresses interest in knowing the E.-Syr. Cath.’s view on an obscure phrase in Psalms, or when a Jewish redactor rewrites the Peshitta of Proverbs into a Targum (Sokoloff, 404–5; Weitzman, 109–11). A more considered interest was found in the period of Humanism and Enlightenment, e.g., with A. de’ Rossi and, more sporadically, with B. de Spinoza (d. 1677).

The eastward spread of Christianity from Palestine must have affected the Jewish communities and the Semitic, largely Aramaic speaking, populations of Syria and Mesopotamia. Some of the earliest Christian preaching must have been done in Aramaic, even though there is very little evidence. At the same time, by the beginning of the Christian era, Hellenism and Greco-Roman culture had a strong presence throughout the Near East, and Greek soon became the primary language of Christianity. Not surprisingly, therefore, there has been an ongoing discussion among scholars as to whether the Jewish stream of ideas or the Greco-Roman one was more decisive in the birth and early development of Syr. Christianity. There is reason, however, to assume that Judaism was a determining factor in the origin and early development of Syr. Christianity, based on the fact (1) that Syr. Christians, probably in the late 2nd cent., received the OT Peshitta from Judaism (regardless of whether the translation from Hebrew was made prior to its being adopted as the Syr. Christian Bible, or was made by Syr. Christians with a Jewish background); (2) that early Syr. literature occasionally reflects non-biblical phraseology of the Jewish Targumim (e.g., Brock 1995); (3) and that early Syr. liturgy exhibits features of Jewish origin (Rouwhorst).

Somewhat related to this is the question of Syr. Christianity’s relationship to so-called Jewish Christianity, i.e., forms of Christianity represented by people who, mostly of Jewish origin themselves, continued to identify as Jews and remained faithful to Jewish customs and rituals (such as circumcision and food laws). As evidence for the existence of Jewish Christians in Syria, one may point to the Didascalia Apostolorum (3rd cent.), which most likely was written in Syria and which in some sections clearly reflects a Christian community that was composed of both Gentiles and Jews (who had to be discouraged from identifying too closely with non-Christian Judaism). This text, however, was written in Greek and may not be representative of the situation in the heartlands of Syr. Christianity; on the other hand, the text’s reception and popularity in Syriac, most likely from the 5th cent. onwards, indicates that its content was seen as relevant to Syr. Christianity. The Pseudo-Clementine writings (see Clement of Rome) also reflect Jewish understandings of Christianity (see most recently Reed). Written in Greek, probably in the 3rd cent., these texts were translated into Syriac and parts were included in the earliest dated Syr. ms. (Brit. Libr. Add. 12,150, dated 411).

Recent scholarship has pointed out that in the early Christian period the boundaries between Jewish and Christian communities were far from watertight and allowed for a rather fluid pattern of religious identification. This situation of porous borders may have lasted longer in Aramaic-speaking areas than in the Greco-Roman world; it also may have had a longer history in the Sasanian Empire, where the 4th-cent. Christianization of the Roman Empire had little immediate effect (Becker 2003). In such a situation the interrelationship between Jews and Christians may have been more complex than it was in the Christianized Roman Empire.

Regardless of how strong a presence Jewish Christianity had in the early period, Syr. Christianity from the 4th cent. onwards saw itself as breaking away from Judaism. The two main 4th-cent. authors, Aphrahaṭ and Ephrem, convey mixed messages. On the one hand, a number of themes and ideas of Jewish origin are found in their works and suppose an audience that, at least in part, was well acquainted with Judaism. On the other hand, this common ground with Judaism did not prevent these authors from expressing distance from and rejection of Judaism, including contemporary Judaism. Just as in Greek Christian literature, Judaism was defined increasingly as the opposite of Christianity. The writings of Aphrahaṭ and Ephrem may be read perhaps as reflecting a situation which was still characterized by ongoing communality between Jews and Christians, but in which these very authors were intent on drawing clearer boundaries and creating separation. Anti-Jewish sentiment, which had been largely absent from early Syr. literature, became a factor in the process of Christian self-identification. It may also be telling that it is mainly Aphrahaṭ’s second series of Demonstrations (nos.  11–22), dated to 344, that contains anti-Jewish polemic, while the earlier series (Dem. 1–10, dated to 337) is relatively free from it. In 344, well into the Roman-Persian war and the predicament of persecution, Christians may have needed a more powerful warning that they should not choose the easy solution of retreating to the relative safety of Judaism.

Aphrahaṭ and Ephrem, writing in the Persian-Sasanian Empire and in the Roman Empire respectively, share a number of themes and arguments in their dealings with Judaism, but their tone is very different. To account for Ephrem’s harsh language about Jews (which may have targeted Judaizing Christians rather than Jews themselves), scholars have pointed to Ephrem’s and his community’s own profound Jewishness (Cassingena: ‘«judéité» fondatrice’), which would have contributed to Ephrem’s particular sensitivity. But the general profile of Aphrahaṭ’s community cannot have been much different, and yet his approach is so much milder. Should we ascribe the difference between Aphrahaṭ and Ephrem to ‘personal temperament and inclination’ (Hayman 1985, 427)? Or should the social and political context be taken into consideration? In the Persian-Sasanian Empire, in which Aphrahaṭ wrote, both Judaism and Christianity were minorities in the Zoroastrian society. In the Roman Empire, however, Syr. Christianity soon became part of the emerging imperial orthodoxy, which in Ephrem’s day was in the process of asserting itself, although it still was fragile (as the short reign of Emperor Julian showed) and weakened by internal division. Might this difference have contributed to setting a different tone for Aphrahaṭ, on the one hand, and for Ephrem, on the other? But even within the corpus of Ephrem’s writings the degree of anti-Jewish polemic differs widely: the Commentary on Genesis (a work with many ‘Jewish’ features) and the Prose Refutations (dealing with different ‘heretical’ doctrines) have very little anti-Jewish polemic; the anti-Judaism of the Commentary on the Diatessaron reflects the language of theological debate (Morrison); and some of the Hymns are passionately anti-Jewish.

Anti-Jewish literature continued in Syr. Christianity, without ever becoming as prominent as it was in Greek or Latin Christianity. And again, marked differences are found, such as between Yaʿqub of Serugh’s harshness and his contemporary Narsai’s mildness (Frishman). Here again, one author is writing within the Roman Empire and the other as a member of a minority group in the Persian-Sasanian Empire. In addition, these authors belong to different theological traditions, which may have had a different impact on their approach to Judaism. As dyophysite Christology and Antiochene biblical interpretation were often portrayed by opponents as being (nearly) identical to Judaism, the use of anti-Jewish argument may have become, for those of the Antiochene tradition, less attractive.

From the mid-8th cent., when both Jews and Syr. Christians had become minority groups under the dominance of Islam, a report is preserved of a disputation that was held in the region of Ḥimṣ between Sargis the Stylite (it is unclear whether he was a Miaphysite or a Chalcedonian) and a Jew (ed. Hayman). While the text contains a number of stock arguments of anti-Jewish polemic, there also is a remarkable passage in which the Jewish interlocutor mentions those Christians ‘who associate with us in the synagogue, and who bring offerings and alms and oil, and at the time of the Passover send unleavened bread …’ (22.1, ed. Hayman, 72; transl. 73–74). Sargis is unable to challenge this description, but portrays these people as ‘sick and weak’, not able to walk on the king’s highway. Once again we seem to be confronted with porous borders, which allow for multiple religious identifications.

In addition to occasionally targeting the Jews in their theological polemic, Syr. Christians also had a genuine interest in Judaism. Their main source for post-biblical Jewish history was Josephus’s ‘Jewish War’. While a Syr. translation is preserved only of the Sixth Book, quotations from other books in Sargis the Stylite’s ‘Disputation’ and elsewhere (in a Miaphysite florilegium, possibly of the 6th cent., preserved in ms. Dayr al-Suryān 28, and in Dionysios bar Ṣalibi’s Treatise against the Jews) suggest that a full translation once existed. This work was used for purposes well beyond that of polemic. Yaʿqub of Edessa had a keen interest in Jewish writings, such as the ‘Book of Enoch’ and ‘Jewish Histories’ (tašʿyātā yudāyātā, a work related to ‘Jubilees’), whose authenticity and usefulness he defended, even against more negative views in the earlier tradition (Adler). He was also familiar with certain Jewish traditions, such as the pronunciation and writing of the Tetragrammaton, and he was aware of the importance of the Hebrew language, of which he had some, albeit rather limited knowledge (see Salvesen). Cath. Timotheos I as well relied on Jews, who in some cases were converts, for information about the Bible. A common practice in biblical commentaries is the quotation of alternative readings from the ‘Hebrew (Bible)’ (along with those from the Septuagint), which either agree with the Masoretic text or, more often, reflect later Jewish interpretations (see, e.g., Ter Haar Romeny 2001). Interest in Jewish sects is found in several Syr. authors, the latest of whom is Dionysios bar Ṣalibi (Brock 1977). In his ‘Treatise against the Jews’, probably the last such work to be written in Syriac, he included an overview of Jewish sects, largely based on Epiphanius of Salamis’s Anakephalaiosis, expanded with information taken from Josephus’ ‘Jewish War’ (Book II,160–6). Bar ʿEbroyo’s attitude towards Judaism is largely irenic. While until recently it was assumed that he was of Jewish descent (‘Son of the Hebrew’, his father being the physician Ahrun), most scholars have now abandoned this view, linking his name instead to the village of ʿEbro, on the Euphrates. There is very little evidence of conversion from Judaism to Syr. Christianity in the Islamic period and, more generally, contacts between Jews and Christians are very poorly documented. Canonical collections include rules urging Christians to work on the Jewish Sabbath, prohibiting bishops and clergy from celebrating Jewish festivals, and warning Christians not to accept unleavened bread from Jews (Kawerau 94). Here again we may be dealing with attempts by the church leadership to create a separation that did not always exist in daily life.

For the later period, we have an interesting example of the co-existence of Jews and E.-Syr. Christians in Iraqi Kurdistan. From the early 17th cent. onwards, benefitting from improved living conditions, both Jews and Christians started writing down their vernacular Neo-Aramaic languages, which were closely related and mutually understandable. Borrowing the script from their respective authoritative traditions (Hebrew and Jewish Aramaic for the Jews and Syriac for the Christians), they proceeded in very similar ways, turning in the first place to liturgical or para-liturgical texts. This ‘areal phenomenon’, involving both Jewish and Christian communities (A. Mengozzi, Israel of Alqosh and Joseph of Telkepe [CSCO 590; 2002], 16), seems to presuppose a rather unproblematic relationship between the two religious communities. As a matter of fact, Aramaic-speaking Jews and Christians lived together peacefully in Iraqi Kurdistan until around 1950, and in Iran even later. Among the villages and towns in which Jews and Christians lived in close proximity to each other, the following deserve to be singled out: Alqosh, where Jews and Christians went on pilgrimage to the tomb of the prophet Nahum (Fiey, Assyrie chrétienne, vol. 2, 396–400); Zakho (see most recently A. Sabar, My father’s paradise [2009]); and Shosh (ancient Bashosh; see Fiey, Assyrie chrétienne, vol. 1, 259). An E.-Syr. ms., Brit. Libr. Add. 25,875, dated 1709/10 (Wright, Catalogue, vol. 3, 1064–69) contains a Hebrew alphabet and some additional writing in Hebrew, including a part of Ps. 22 in Hebrew script, even though the text is Syriac. In the 20th cent., however, the political situation in the Middle East added a new layer of tension to the relationship between Jews and Syr. Christians.