Most heresies come from questions that people answer themselves, and the early church developed largely by answering these questions. The heresy or Twisted Truth of Arianism came from a Christian priest who was a literalist and believed God and Jesus could not be the same. The father was not the son, Jesus was not God incarnate. That's a problem for Christians who accept the spiritual truth that Jesus IS God. Because if Jesus was "just another great guy," why would we want to follow Him? Christianity is the only religion based on God choosing to enter the world in flesh to show love to humans while other religions are about humans reaching up to God. It's a big difference.