In this lecture, we explore the background, rise, and teachings of Islam, now the world’s second largest religion. We trace its origins in Arabia, the life and revelations of Muhammad, the preservation of the Qur’an, and the rapid expansion and intellectual contributions of Muslim civilization. Along the way, we define central concepts such as īmān (faith), sunna, ḥadīth, jihād, ḥajj, and umma. The second half of the lecture turns to theology, comparing Islam’s insistence on the oneness of Go...