Atheism is irrational.

[Tonus]

3. So there must be something that doesn't need a cause starting the chain.

How do we determine what that thing is?

This, to me, is what shows that none of the interventionist Gods that people believe in are real. For all of its flaws, the argument from design makes intuitive sense to people, and since the other explanation for the existence of the universe is "we don't know" it is that much more compelling to a mind that strongly desires closure in all matters. But that argument only gets us to one or more creators. It tells us nothing about it or them. NOTHING.

So it's not surprising that throughout human history our Gods are too numerous to count and they come in every possible variety. Even today --after centuries of discussion and argumentation and interpretation and philosophizing-- people cannot agree on who or what this God is and what it or they want. Ask a bunch of people of the same religious denomination to describe God and you will get a different description from each one. If all of these 'proofs' of God can't get us any further than "God has to exist" then there is no way to determine who/what it/they are.

I'm willing to grant the claim that a God is necessary just so that we can watch as the multitude of religions and denominations go about determining just who this necessary being is. How long before we go from arguing about how to apply metaphysics to a room full of dead zealots?