I’ve always been ill at ease with the term “Judeo-Christian.” As someone from a Muslim cultural background I was minimally familiar with the tenets and principles of the Islamic religion. As someone who was socialized with both Jews and Christians I was reasonably familiar with the outlines of both faiths. When my teachers wouldrefer to the “Judeo-Christian” tradition I simply felt that something was off. Talking to Jews about their religion it seemed, to me, to resemble Islam more than what the Christian children described. Additionally, on occasion my family would purchase kosher food because it was always halal. Unlike Christians both Muslims and Jews tend to avoid pork and circumcise (though Jews obviously have no problem with alcohol). As I grew up I had the experience multiple times of Jews, American and Israeli, attempt to establish a bond with me when first meeting me by emphasizing the relative similarity of Judaism and Islam as opposed to Christianity (the assumption being that I was Muslim). Simultaneously, in my reading I stumbled upon peculiar facts. For instance, while rabbis have long had debates about whether Christian churches are houses of idolatry (e.g., could Jews buy land from Christians and use a former church facility?), there was never any such concern about Muslim houses of worship, because Muslims were incontrovertibly monotheists who did not use images in their worship.
Recently I’ve been reading Essential Talmud by Adin Steinsaltz, as well as some extracts from the Talmud proper. The material I encountered has confirmed in my mind that empirically the term Judeo-Christian is a farce when it is juxtaposed against Islam (though not against a Dharmic religion). The mode of Talmudic casuistry has the same intellectual flavor as Islamic jurisprudence. Some religious scholars have emphasized that while Islam & Judaism are religions of orthopraxy, Christianity is one of orthodoxy. Roughly, Islam & Judaism are faiths where the details of belief once particular necessary preconditions are attained are less important than punctilious implementation of the law. In contrast, Christiantiy has a long history of abstruse theological controversies and debates. If the Abrahamic faiths can be viewed as a fusion between Semitic theism, religious legalism and Greek philosophical formalism, one can characterize Christianity as emphasizing the first and last elements, while Judaism & Islam put the focus on the first and second elements. Both Islam and Judaism did give rise to movements which attempted to inject Hellenistic philosophy into the religion early on in the development of the historic traditions; but both these attempts (the Mu’tazili school in Islam, and the Hellenistic variants of Judaism during the Greco-Roman period) failed in their overall project (some Jewish thinkers were suspicious even of Maimonides philosophical forays). In contrast, early on Christianity became de-Judaized and St. Paul established the precedent that gentile converts to Christianity did not have to follow Jewish law.
Of course these are broad generalizations, and cultures are not sealed into separate compartments. Certainly details of theology and belief are critical in distinguishing some esoteric Shia groups from the mainstream of Sunni Islam. Some Christians have also shifted back toward more Judaic customs, especially with the splintering of sects after the Reformation. But, there is one major issue in the American context which I think is important when it comes to the perception of a Judeo-Christian co-dominion, and that is the prominence of Reform Judaism. Reform Judaism is a relatively new movement which arose in 19th century Germany and has flourished in particular in the United States. According to the American Jewish Identity Survey the Reform movement is the largest group of religiously identified American Jews. A few years ago I read a book, One People, Two Worlds, which consisted of a discussion between a Reform & Orthodox rabbi. One interesting point that illustrates the chasm between the two groups is that the Orthodox rabbi kept complementing the Reform rabbi’s knowledge of the Hebrew Bible (similar to the Christian Old Testament), but, he encouraged him to study the Talmud and become “religious.” The issue here is that the Orthodox rabbi never truly could engage the Reform as a religious Jew, because to him religious Judaism is the historical tradition which emerged out of the redaction of the Babylonian Talmud and requires adherence to the Jewish law. Many Christians simply assume that Judaism is Christianity without the New Testament, that is, it is a religion based upon the Old Testament in the form of the Hebrew Bible (which differs a bit in the books and their order from the Christian version). For most of the past 2,000 years this was very incorrect insofar as Rabbinical Judaism, what we today term Orthodoxy, was grounded in an enormous corpus of commentary and exposition of the Oral Law which became the Talmud. For Jews to turn away from this legalism they would not have to just interpret the Hebrew Bible in a more allegorical fashion (so the 613 commandments aren’t literally intended or relevant anymore), they would have to do away with the relevance of the Talmud to Jewish life, when the fact is that that book has been central to Judaism from 500 CE to 1800 CE. Reform Jews to a great extent did just that, and some Reform revisionists contend that their tradition is a form of Judaism which is the heir to the practices of the Saducees or the Hellenistic Jews. In this way, they recast their tradition not as a diminishing of Judaism (e.g., the abolition of adherence to law) but the rebirth of an alternative tradition within the faith. There is another group today which is likely the heir to Hellenistic Judaism: Christianity. Rodney Stark in his The Rise of Christianity argues that Hellenistic Jews were the core of the early Christian Church.
And so there you have a way to make the term Judeo-Christian be more than propaganda, Reform Judaism like Christianity tends to reject legalism and ground its identity in a statement of creeds and principles of belief. Over the past century Reform has become more traditionally Jewish (e.g., in the 20th century they reaffirmed that the Jews were a nation, which they had rejected in the 19th), but it still remains distinct from Orthodoxy in its soft-pedaling of adherence to Jewish law. Reform Judaism arose in Germany during the 19th century when Jews were allowed into the mainstream of gentile society. It was an attempt to “normalize” Jews so that they were no longer a people apart, tearing away the separation which ritual law enacted (some Reform rabbis even rejected circumcision) and remaking Jews into a minor unitarian denomination with a culturally particular past. Ultimately Reform was a failure in Germany for obvious reasons (though intermarriage, conversion and secularization already took a large toll before the mass exodus and extermination of the community during the Nazi period), but it flourished in the United States as an avenue for the assimilation of eastern European Jews into the American cultural matrix. It allowed Jews to retain their religious distinctiveness without being bound to Jewish laws. One reason most Americans find the idea of Judeo-Christianity so plausible is that the Jews they encounter are disproportionately Reform or secular. To caricature it one could sum up the minimalist Judaism normative in the Untied States as mainline Christianity with the Son and the Holy Ghost subtracted. In contrast, it is in Orthodox Judaism that the similarities to Islam become stark as the legal dimension of the faith comes to the fore. Though Orthodox Judaism and Islam give due respect to their foundational written scriptures, the Hebrew Bible and the Koran, both are incomprehensible without consideration of the mass of commentary built around the original written law. In Judaism this would be the collection of writings which comprise the Talmud, and in Islam it would be the Hadiths. I predict that there is a strong chance that in this century we will see a “Reform Islam” coalesce in the West which is analogous to Reform Judaism, an adherence to a minimalist Koranically inspired religion which gives short-shrift to the relevance of the Hadiths in the modern world. In this way, there will be a dyad of Judeo-Christian-Islamic and Judeo-Islamic (there are legalistic movements in modern Christianity, but obviously unlike Islam or Judaism they are created de novo rather than looking back to a long history of commentary and precedent).
So where does that leave us with the term Judeo-Christian? Language is what you do with it. My own suspicion is that when people use the term Judeo-Christian they really mean Western, but Western is not a PC term for contemporary discourse. Haredi Jews are not truly part of the West the way Reform Jews are. And Reform Jews are of the West while Muslims are not, at least for now. The Sephardic Jews don’t have a Reform tradition because they did not crystallize in a Western cultural matrix. Since I tend to favor precision over expedience in language I generally challenge or confront friends or acquaintances who use the term Judeo-Christian in a manner which has inferential significance.