There are three major religions that has Abraham as a major patriarch. They are Judaism (Jews), Christianity (Christians) and Islam (Muslims). God promised Abraham that his seed would be enumerable as a result of his faithfulness (Gen 22:17). read more
Muslim faith did not split from christianity. It arose in what is now Saudi Arabia and the prophet Mohamed knew Jewism and Christianity. The prophet died in 632 AD. South west Europe was christian including Ireland. England was just approached by Benedictine monks. Europe north and east of the rivers Rhine and Danube were pagan. read more