Everyone knows his name. He was, and still is, one of the most influential figures of all time, yet most of us have little real sense of the man himself. A favorite question of those asking about my new book, “The First Muslim,” is thus what surprised me most in my research. Or rather, what might surprise them.

The first and most important teaching of Islam is the oneness or uniqueness of God (Allah). This teaching is the first part of the first pillar of Islam and the first article of faith that Muslims must believe. Islam teaches a oneness of God that goes beyond the English term “one.”