They share the same source material, the Torah. The Christians just called it the Old Testament and then added their bit about who they thought was the "messiah." Islam then took the Christian version, recast the "messiah" as a great prophet and added their bit about the super ultimate prophet. 

Aside from that the three Abrahamic religions are pretty much the same. This is why fundamentalist Islamic sects have so much in common with fundamentalist christian groups when it comes to how they view women and LGBTQ folks. Thank the founders for the first amendment which makes us a secular nation and not theocratic!