"Why not?" Surely, that is the question that some Jewish-Christian interfaith couples may very well ask themselves when considering the possibility of affiliating with a Messianic Jewish congregation. Messianic Judaism is a movement in which Jewish beliefs as well as faith in Jesus are taught, and rituals from both faiths are practiced as well.
These congregations may seem, at first glance, to provide the "best of both worlds" for interfaith couples. Jews may feel at home because the worship environment of a Messianic congregation may seem similar to that of a liberal synagogue, with men (and, possibly, women) wearing kippot (skull caps) and tallitot (prayer shawls), and with familiar prayers and melodies. Christians may feel at home because Jesus (referred to as "Yeshua," a Hebrew name derived from the word meaning "salvation") figures prominently in the liturgy. A Messianic Jewish sanctuary might feature a baptismal font next to an aron kodesh (holy ark) containing Torah scrolls. What could be bad about a house of worship in which features of the religious traditions of both partners are interwoven?
If an interfaith couple is asking, "Where can we go where elements of both of our faith traditions can be honored and incorporated into a common way of life?" then it may seem that a Messianic Jewish congregation could be a good fit.
But is it? Judaism and Christianity are two great faith traditions that have long differed substantially from one another. Despite outward appearances, Messianic Judaism is not a harmonization of the two. One example will suffice. The belief that God is indivisible and incorporeal (i.e., has no physical form) has long been central to Judaism. This is inconsistent with the belief that Jesus was a semi-divine being gifted with supernatural salvific power. By embracing a doctrine that is so intrinsic to one faith and so foreign to the other, Messianic Judaism is hardly a fusion of two great religions.
Moreover, membership in a Messianic Jewish congregation will not help interfaith couples who would like to be connected with the Jewish community. On the contrary, the Jewish community is likely to view them with intense suspicion and hostility.
Why is this? Why are so many Jews antagonistic toward Messianic Judaism? The fundamental reason is that virtually all Jews identify faith in Jesus as the Messiah as the essence of the divide between Judaism and Christianity. In other words, if a Jew comes to believe that Jesus is or was the Messiah, then he or she has in fact become a Christian. Such a person might still remain a Jew in an ethnic sense, but most Jews would not agree that he or she believes in or practices the religious tradition known as Judaism. Messianic Jewish congregations, to most Jews, are churches rather than synagogues: places where Christianity rather than Judaism is practiced and promoted. And yet such institutions fail to identify themselves as churches. They fail to acknowledge that Christianity is taught within them. Rather, they teach that the acceptance of Jesus as the Messiah can be consistent with a Jewish religious identity. In fact, they go further than this. The stated "greater goal" of the Union of Messianic Jewish Congregations, for example, is "welcoming Yeshua back into the midst of the Jewish people as Lord and Messiah."
This gives rise to great concern and suspicion among Jews. For hundreds of years, Jews have been targeted by certain Christian groups for conversion, and many Jews understandably see Messianic Jewish congregations as just the latest manifestation of this phenomenon--which, if successful, would lead to the disappearance of Judaism. Hence, the Jewish community (by which I mean the organized world of synagogues, Jewish community centers and other Jewish communal organizations) is virtually uniform in its rejection of Messianic Judaism.
This fairly uniform hostility by Jews toward Messianic Judaism may seem unfair, and may seem to be a striking exception to the pluralism that otherwise characterizes liberal Judaism. That, in any event, is what Dan Cohn-Sherbok, a scholar of Messianic Judaism, argues in his book, Messianic Judaism. If liberal Jews themselves reject many of the fundamental principles of traditional Judaism, Cohn-Sherbok asks, then on what basis can they justifiably reject Messianic Jews?
Cohn-Sherbok makes a case for accepting Messianic Judaism as a legitimate expression of Judaism in today's world. But unfortunately for interfaith couples who may feel drawn to embrace it, few in the organized Jewish world agree with him. Believing in Jesus, accepting the New Testament as holy scripture, celebrating Jesus' resurrection on Passover--all of which are common in Messianic Jewish communities--these are simply unacceptable for the vast majority of Jews today.
I believe that Jewish-Christian interfaith couples should learn about both Judaism and Christianity in order to make informed decisions about their family's religious identity. They should seek guidance from interfaith professionals and/or sensitive clergy to sort through the complicated issues involved. Couples can gain perspectives that can open up suitable possibilities that can also allow them, should they so desire, to develop strong connections with the Jewish community.
In general, it is best to acknowledge religious differences. It doesn't do justice, either to Judaism or Christianity, to suggest that the nature of Jesus and his role in one's spiritual life is not a significant issue. My view is that it is better for individuals to choose a particular religious tradition (whether it be one of the movements in modern Jewish life or a Christian church), than to try to have it both ways.