How would the world be different if.....?

Mohammad were never born. I ask because the area that his followers took over immediately after his death (N. Africa, Middle East, Turkey etc) were Christian regions for at least 600 years until they were conquered. If all these areas plus Western Europe, Slavic Europe, the Americas, Pac Islands, Africa, Australia, and the Christian regions of Asia were still all Christian today what would the world be like. Two HUGE civilizations (ie, China and India) plus a few other regions of Asia would theoretically still be non-Christian but maybe the world would have united under Christianity already. The world would be at least 2/3 Christians if not more if it weren't for Mohammad. What other consequences do you all think would exist from his absence in history. And what would a world without religious differences look like?