Share. Christianity developed out of Judaism in the 1st century C.E. It is founded on the life, teachings, death, and resurrection of Jesus Christ, and those who follow him are called Christians.. Christianity has many different branches and forms with accompanying variety in beliefs and practices.t is founded on the life, teachings, death, and resurrection of Jesus Christ, and those who follow him are called Christians.. Christianity has many different branches and forms with accompanying variety in beliefs and practices.