The most significant mystical event in Muhammad’s life was the night journey he took to Jerusalem on the back of a lightning steed. Muhammad worshiped there with his predecessors and then was lifted up to the seventh heaven, where he communed with Abraham, Moses, and Jesus before being ushered into the presence of Allah.
The purpose of the Koran, to borrow Jesus’s words, was to fulfill the law, not to break it. It took warfare to spread the new faith, but just over the horizon was a Paradise in which one God welcomed all believers. We can say that Islam brought monotheism to replace polytheism—the Arabs got one God in place of many. But the message was more universal. Allah wasn’t Yahweh dressed in a caftan. He was the One, an all-pervasive presence that upheld the cosmos.