Complex sentence: He left the school prematurely after rejecting the teachings of the Bible, left behind his clothing and belongings, and retreated into the mountains of Matepi where he began to form a personality cult around himself as the Messiah, "Black Jesus".
Split into simpler sentences: He left the school prematurely after rejecting the teachings of the Bible, and leaving behind his clothing and belongings. He retreated into the mountains of Matepi where he formed a personality cult around himself as the Messiah, "Black Jesus".