Years ago, I was sitting with a group of young married couples, most of whom were Jewish. One of the non-Jewish spouses in the group said something to the effect that he had considered converting to Judaism but decided he could not. Someone asked, “Why not?” To which he replied, “Oh, I can’t convert to Judaism. I don’t believe in God.” Someone else present immediately slammed his hand on the table in objection, “And what does that have to do with it?”
I don’t remember anything else about the conversation, but what I’ve related here suffices to illustrate an important and common view about Judaism: that it’s primarily about what one does—not what one believes. (This of course is in contrast to one common understanding of Christianity—that it is primarily about what one believes.) Whether true or not (and for the record, I am not so sure), this view is widely held among contemporary Jewish intellectuals and can be traced back to one of the greatest modern Jewish intellectuals of all time, the German-Jewish philosopher Moses Mendelssohn (1729–1786). For him, Judaism is a religion of revealed law. It is for this reason that Jews have expended much more effort delineating practices, producing works like the Mishnah and the Shulkhan Arukh, and comparatively less time developing fixed creeds—which have indeed been a priority for many Christians.