Christianity, Islam, and Judaism are all Abrahamic religions.
To break it down, essentially, different flavors of the same core "food."
Christianity believes in Christ (Jesus Christ) as the messiah and savior. Judaism does not consider Christ to be the messiah, and are still waiting. Islam believes that Jesus was a prophet of the lord (same lord, god, etc) but Mohamed was the first, and thus best (hearkening back to early internet "first" posts that were utterly pointless).
Its all the same shit, but go on.