How can you be sure that God doesn't exist?

[Gwaithmir]

The Christian God is defined by mainstream Christianity as being all-knowing, all-loving, all-powerful, and all just. Yet even a cursory reading of the bible reveals a God who is cruel, unjust, tyrannical, unloving and eternally vengeful. Ergo, the Christian God does not exist by reason of self-contradiction.

An all-loving, all-powerful, all-knowing God, by definition, cannot create evil or permit evil to exist in the world. And yet, evil exists. Ergo, God, as he is defined, does not exist on the grounds of self-contradiction.

The law of conservation of matter and energy states that the total quantity of energy in the universe remains the same. Matter and energy are interchangeable, but neither can be created or destroyed. Ergo, the universe has always existed and will always exist in one form or another. God is unnecessary by the Principle of Parsimony.

The natural histories of religions are well-documented. The behavioral causes of religions are well-known. There is no evidence that gods and religions are the products of anything other than human ingenuity and imagination. Ergo, atheism is rational and skeptically unassailable.