Betrayed by the Church, I Allied with the Evil God and Killed the Hero

After serving the church in another world for 2 years, Edith is deemed 'too dangerous to be left alive' because of something called a Contract Spirit he has living inside of him. He is betrayed and left for dead in the deepest depths of the Dungeon ruled over by said church. Then not long after his Contract Spirit awakens inside him and promises to help him get stronger so he can enact his revenge.