What happens to morality if there is no God?

If there is no God, there is no authority to decide what is good or evil except by oneself. Therefore there is no objective moral value to anything, and if you have power to get away with it then and murder and pedophilia and stuff like that is a-okay. If there is no divine accountability at the end of one's life it matters not if you live as a saint or as a ruthless tyrant, you both go to the same place.