Jul 31, 2007  · For a complete list (which also includes atheism and agnosticism, see the Wikipedia article or the Encylopaedia Britannica chart). 1. Christianity [Abrahamic, 27 AD] 2.1 billion adherents [Wikipedia | Britannica | Beliefnet] Christianity is a monotheistic religion which is based on the teachings of the Old Testament and Jesus of Nazareth. People persecuted for their religious or political beliefs. have been added to the. Five EU members…