How and when did Muhammad decide that the Abrahamic god was the one and only God? According to one early oral Muslim tradition, Muhammad’s wife had a wise old cousin who was a Christian. When Muhammad had his initial revelation, it was so disorienting—Was he going crazy? Was he demon-possessed?—that he sought guidance from his wife, and she consulted this cousin.

If indeed Muhammad fleshed out an initially vague religious experience with the help of a Christian, that could explain why he concluded that his mission was to spread a monotheist message, and, more specifically, the message of the Abrahamic god; especially if, as that early Islamic tradition has it, the Christian in question had long believed that God would send a prophet to the Arabs—and declared upon hearing of Muhammad’s experience, “Verily Muhammad is the Prophet of this people.” This is the kind of pronouncement that could help a seeker with messianic leanings but no clear mission fill in the blanks.

Even aside from the Christian cousin-in-law, Muhammad had chances to learn about the Judeo-Christian God. There may have been pockets of Christians and Jews in the Meccan vicinity, and there was a sizable Christian community in Yemen, one of Mecca’s two main trade partners. And the other big trade partner, Syria, was part of the Byzantine Empire and hence heavily Christian. Muhammad is said to have traveled to Syria as a boy with his uncle on trade trips.

He would probably have carried an open attitude toward Syrian religion. Mecca was a polytheistic society that, in classic ancient fashion, was tolerant of the gods of trade partners. In fact, Mecca’s famous shrine the Ka’ba—today the destination of the hajj, the annual Islamic pilgrimage—was in pre-Islamic times surrounded by idols of gods favored by various tribes and clans, and this pluralism seems to have lubricated commerce. According to one early Muslim source, a Christian had been allowed to paint an image of Jesus and the Virgin Mary on an inner wall of the Ka’ba—the sort of formalized respect for the beliefs of trade partners that would have been unexceptional in an ancient polytheistic city.

In this case the respect probably went beyond the formal. The Byzantine Empire was more cosmopolitan, more technologically advanced, than Arabian society, and the culture of a powerful neighbor often holds a special fascination to a less developed people. So long as that power isn’t viewed as an enemy, the fascination can be alluring.

This leads to one way of looking at Muhammad—as a man who had the ingenuity to fill a wide-open spiritual niche. He took a foreign god that was already making inroads in Arabia and became that god’s official Arab-language spokesman. To put it in modern commercial terms, it’s as if no one before Muhammad had thought to secure Arabic translation rights to the Bible, even though demand for such a book was taking shape.

The Koran itself comes close to saying as much: “Before this, was the Book of Moses.… And this Book [the Koran] confirms (it) in the Arabic tongue.”

However, there’s a crucial difference between this line and the Muhammad-as-translator analogy. In the translator scenario, Judeo-Christian theology is transmitted to Muhammad by contact with Jews and Christians and/or their scriptures. In the Koran’s scenario, Judeo-Christian theology was transmitted to the Jews and Christians by God and then to Muhammad by God. When God, in the Koran, tells Muhammad that he has “made it an Arabic Koran that ye may understand: And it is a transcript of the archetypal Book,” the archetypal Book isn’t the Bible. Rather, the archetypal book is the word of God—the Logos, as some ancient Christians and Jews would have put it—of which the Bible is equally a “transcript.” Muhammad didn’t get the Word via Moses. Rather, like Moses, he had a direct line to God.

So Islam, by its own account, isn’t descended from other Abrahamic religions, even though it is rooted firmly in the Abrahamic lineage. Yes, Islamic tradition may highlight Muhammad’s contact with a Christian relative, but the idea isn’t that the relative was an invaluable tutor in Christianity; more important was his role in helping Muhammad see which god was already doing the tutoring.

This distinction would have been crucial to Muhammad. The way to attract a devoted following in those days was to have special access to the supernatural. Just having access to a cousin-in-law conversant in biblical scripture wouldn’t be very impressive. Indeed, that Muhammad’s “revelations” were in fact coming from human sources is an allegation Muhammad’s enemies made in trying to blunt his appeal. As the Koran describes the charge, Muhammad’s message was dismissed as “tales of the ancients that he [Muhammad] hath put in writing! And they were dictated to him morn and even.” At one point the Koran even addresses a specific accusation about who was doing the dictating. “They say, ‘Surely a certain person teacheth him.’ But the tongue of him at whom they hint is foreign, while this Koran is in the plain Arabic.” Case closed.