Philosophical Underpinnings for Rejecting God

[Jenny A]

Guys. Hello.

I understand that Atheism is a rejection of existence of God, or more broadly speaking (and correct me if I am wrong) rejection of all metaphysical realities. For example, Afterlife, Angels, Heaven/Hell, Satan, etc.

But what is the philosophical underpinning for rejection of God?

Is it Naturalism? Empiricism? Materialism?

Thanks.

Atheism is not a philosophy.  It is a single position on a single issue:  the existence of a god or gods. Atheism is a lack of belief in a god or gods. That's all.  

It is not a general rejection of an afterlife, or any other supernatural idea although many atheists not believe in the supernatural generally.  Angels and Satan on the other hand are gods (supernaturally powerful beings) and lack of belief in them is required.

Many atheists including myself reach this position through skepticism, but it might be reached by any number of means including simply never have been indoctrinated in a religion.  No stance on naturalism, empiricism, or materialism is required.  Again, atheism is not a philosophy, it is a position on a single issue, the existence of god.

Nor is it necessary in order to be an atheist to believe that all or indeed any gods have been disproved. It is quite common to lack a belief in something's existence because that thing has not been proved and not because it's existence has been disproved.  Right now I lack a belief that there is a million dollars in my crawlspace, but I haven't proven it isn't there.  In fact is not really possible to prove the lack of existence of anything.

Nor yet is it a belief in a god coupled with a decision to reject that god.  Even if you are opposed to the only god you believe in, belief in a god would preclude you from being an atheist.  It's definitional.