Gnosticism was an important sect of early Christianity which believed that, in order to achieve salvation, one much achieve knowledge (gnosis), and that all matter is evil, while the spirit realm is good. The Gnostics saw Jesus as a being who was part-human and part-God, and that he left his physical body before his death on the cross so that only the human part died. They also saw God as an eternal, unknowable, and undefinable spirit who spawned a large number of lesser spiritual beings. The Gnostics, whose belief that Jesus was inferior to God, were persecuted by mainstream Christians as "non-Orthodox" heretics, and the Christian Church ultimately devised the Trinity to justify how Jesus was both man and God.