The worlds biggest religion which is based on the teachings of jesus christ. christianity developed out of judaism in the 1st century. followers of christianity are called "christians". christianity has three major branches, Roman Catholicism, Eastern Orthodoxy, and Protestantism. most adherents of christianity were in the west. traditional christian beliefs include the belief in the one and only true god, who is one being and exists as father, son, and holy spirit.