The reason I don’t believe in any god or gods is simple, there is no reason to believe in any god or gods. There is no reason to use a god as an explanation for anything and there is reason to doubt the existence of any god or gods.

All currently available evidence tells us that all thing happen through natural processes. Every thing we have figured out, from lightening to geology, from evolution to the inner workings of the human body has not only been explained by natural processes but those explanations have been tested and verified. But that of course doesn’t mean that what we have yet to explain (or have been explained but the explanations have yet to be verified) has natural causes behind them but to suggest that what we have yet to explain has a super natural cause is not only a cop out (explaining the unexplained with the unexplainable) but a logical fallacy (argumentum ad ignorantiam (Argument from ignorance)) as well.

For example, science has yet to verifiably explain the what the universe came from or what was before it, but this in no way means a god or gods where responsible for it. In fact I can think of 3 natural explanations for the where the universe came from off the top of my head.
1. The fabric of time and space itself is eternal (its always existed) and that some very rare (say on average it happens every 10 to the 120 power years (that’s a 1 and a 120 0’s behind it (to put that in perspective the universe is only about 13,500,000,000 years old))) phenomenon happened and science has yet to discover and verify the phenomenon or possibility of it.
2. There could be a multiverse with many if not infinite universes and our universe could have been born out of another universe through a natural process.
3. This is sort of a combination of 1 and 2. It comes out of M-theory. Two branes (as in membranes (the fabric our universe)) collided resulting in the big bang.
of course the first two are unverifiable since I made them up off the top of my head and the third is very far from verified but they are a good example that you do not need a god or gods to explain the oriien of the universe or anything else.

And of course there are problems with the god idea. Where dose the god or gods come from? Saying that a god or gods did it just pushed the problem up another level (as with any explanation for the oriien of anything, you just end up asking “where did that come from”) a popular answer is “God has always existed” well I can just take that idea and apply it to space times (as I did above).
Another problem is what the definition of a god is. The simplest definition is as the creator or creators of the universe. On the other end of the spectrum is a god is an omnipotent, omniscient, omnipresent and omnibenevolent bing. While a polytheists definition of a god would nether involves any omnis or creating the universe. Many define god as the Jewish, Christian and or Muslim god. Further confusing the definition of god are modern new age spiritualist religions, make it up as you go along religions (Wika, neo-paganism) and pseudoreligions that are popping up.
God as simply the creator is a very broad and week definition, by that definition an animal that created the universe by accident would be considered God (in another universe where the physics is such that an animal could create a universe by accident)
An omni god (omnipotent, omniscient, omnipresent and omnibenevolent) definition has the omnipotence paradox (could an omnipotence bing create a rock too heavy for it to lift? ether answer takes away its omnipotence) it also has the freewill vs omniscience paradox and omnibenevolents leads to the problem of evil.
But with out the creator and omni aspects the definition of a god is basically a powerful supernal bing. A ghost or demon if powerful enough could be considered a god.
By defining a god as the Christian, Jewish and or Muslim god you then bring all the problems that those/that god have (and it/they have many)

of course none this disproves the existence of a god or gods. But if a god exists, based on all available information it would be a deistic god (A god that creates the universe than steps aside and doesn’t interfere in it or a god that create the universe and hide all evidence of its existence and plants evidence that it all happened by natural processes) but there are logical problems with Deism. First is motivation. Why would god create the universe? Any reason I can think of diminishes God to an alien in another universe. The best one I can think of is God as a scientist and the universe is the result of an experiment or is an experiment being done by God. Though that god would fit the creator definition, that’s not much of a god and I wouldn’t call it a god. And if god is an alien scientist in another universe than why is it needed to create the universe? Why can’t it happen by some natural process within that universe? And Deism still has the problem of “what created God?”

of course some of you are thinking “But you haven’t disproven God and you’ve admitted it.” of course, it very hard to prove a negative and allot of times you can’t but that doesn’t mean you should be agnostic about it. I can’t disprove fairies, dragons, leprechauns, ghosts. alien abduction, and many other things but agnostic about them. I can’t disprove the existence of a god or gods but that doesn’t mean I should be an agnostic.