Religion dominates humanity. Their god rules through power. He is a vengeful jealous and blood thirsty god.

Jesus comes along and starts waking people up. Says his God is all loving compassionate and would never demand you worship anything. He says their god is the devil.

Powers that be don't like this so they kill him. Then to keep people from leaving the church they change their story to make it sound like Jesus was one of them the whole time and he had to die for our sins. He did it for us. Guilt trip city.

There's the new testament.