'God' is a lie. Specifically, the deity of the Torah, Old/New Testament, the Q'ran. Get used to that. The formula for the disproval of this god is based on the simple contradiction of his purported powers that his followers think he has.
Let's revisit an earlier point. There are three qualities this god of theirs is supposed to have. Just ask any Jew/Christian/Muslim and they'll concur about their god these three things about their magnificent, beatific fable. They will agree that thei r big invisible pal is:

Omnibenevolent... all loving. This deity is furthermore supposed to BE love, the source of the simple, warm emotion that we get, the source and cause of generosity, compassion, the end of any notion of suffering, tranquil pleasure... just heap them c ute, fuzzy pink words up, and you got that god right there.
Omniscient... that means this being can percieve anything and everything, knows EVERYTHING, backwards and forwards in time. I mean EVERYTHING. From where you misplaced your wallet when you were sixteen, to where every single sock you lost in the dry er wound up, to how to program in Linux, Unix, C, and a VCR made in any language. Capisce?
Omnipotent... that means all frigging powerful. Their being could play croquet with the planets on a whim, make it rain tapioca pudding at will for sixteen years, make an oak tree grow out of somebody's nostril... you name it, this is supposed to be y our deity- he can do it. Now, just because your being is NOT doing it doesn't mean he CAN'T do it, because then that's NOT omnipotent. If he CAN'T make these irrational things occur... um, irrational, miraculous things, then he's just plain NOT o mnipotent. But he CAN, apparently this being just doesn't, for whatever reasons.
So, BLAM, there you have it.
The religions I mentioned, which happen to be the religions of the most opinionated, self-serving, damage causing, racist, inhumane, accusation flinging, murderous organizations known... and I'm not strictly speaking of institutions such as the Vatican or whatever, will agree that these three things are the qualities of their god, and that THEY ALONE are indeed doing their god's will, that THEIR interpretation of this invisible deity is the correct one.
How pathetic! How loathesome! Do you mean to tell me that a finite, doomed-to-die, stuck-in-flesh human has the 'inside track' on god? That their god is in fact these three things when the world DOES NOT REFLECT that such a being exists? Bullshit, and we will now play a game and see just why not.

Let's start with their assumption that thier god is omnibenevolent by their standards. You know, that all-loving shit. I think that this is the one that is definitely the most wrong. Seriously, taking an emotion that is inspired by the mixture of hormo nes and chemicals that emanate from VERY explained sources such as the pituitary gland and genitals and saying that, "Yeah, this god is just that! The same feeling my nuts/ovaries and brains concoct when I like what I see!" Alright... let's leave this p oint be and move along.
Okay, we have omnibenevolent. Now let's toss in omnipotent. All frogging powerful. Turn skyscrapers into Jello molds, penguins into marshmallows. We get them both side by side in this big badass creator, but we still got suffering, we still have murd er, rape, incest, hatred, loathing, dissatisfaction, suicide, et cetera, things which contradict love and benevolence, kindness and fellowship, and we are NOT seeing the sort of miracles that these archaic books (loaded to the teeth with nebulous analogy and human error) claimed happened thousands of days. We're not even seeing clear proof that these fable-caliber stories even DID happen. Noah's Ark. Enough said.
Now wouldn't this all loving and all powerful god just elimininate suffering? Hmm?
I know the responses. Don't bother trying them, oh decieved, mediochre faithful.
Now let's toss 'omniscient' into this smacked up equation. Omniscience would totally render the feasability of omnipotence and omnibenevolence shattered.
Let's just pretend a moment, play 'devil's advocate', if you will, that this god of theirs is NOT omniscient, that their god indeed might not know shit. That would mean that maybe this god is running a test of sorts, letting us humans wander about with t he 'free will' theory, hurting eachother, committing all manner of atrocities, but just doesn't know what to do to stop the suffering completely without screwing up his precious equation/plan. Limited mind or not, that's just bullshit. That is total cru elty, seeings how this god is supposed to be benevolent. Apparently, 'plans' mean more than harmony. But, the concept of their oh-so-holy god being possibly senile is repugnant to the faithful. Their god is 'all that', after all.
NOW, let's go back to this god being all knowing. He would know exactly what to do to stop suffering, make everyone indeed happy without all the slaughter and sleepless nights and mental disorders and any manner of you-name-it-if-you-think-god-thinks-it s -naughty type of stuff. We would NOT be robots, such an all-knowing god would know how to rig the show so's we'd be perfectly entertaining, free-willed and whatnot without all the bloodshed that's supposed to be 'sinful'.
Okay, let's jump back to playing the 'devil's advocate' a moment and take 'omnipotent' out of the summary of god's qualifications as a creator. Maybe he CAN'T fill canyons with Titleist golfballs, maybe he CAN'T completely de-bug windows 95, maybe he can 't do a damn thing anymore! Maybe he can't do sh*t about 'evil'. He's sitting up there in 'heaven' and bawling his benevolent peepers out because he's impotent. But, since the idea of a handicapped deity would just plain suck the wind out of the sails of anyone faithful, I suppose that this quality would have to remain the most firmly in place. Deities are supposed to be incomprehensibly powerful anyhow. It rounds out their mystique perfectly.

So what does that leave us to play with, in our game of 'devil's advocate'? Why, let me see... Oh! Omnibenevolence! Let's just remove THAT and leave the other two strong and see what we got. Let's see... this god just knows EVERYTHING, and can do ANYTHING. But he doesn't give a flying fuck at a rolling fruit loop- generally speaking of course, in his incomprehensible godly way of not giving a fuck. This god doesn't love EVERYTHING like it s ays so in the bible, no... This god wouldn't be hypocritical, and in fact would be very choosy, picking his favorites and setting them up with a nice afterlife and sending those he hates (not incapable for a god that isn't omnibenevolent) right into hell. This god would delight in teasing people with concepts of the afterlife, heaven and hellfire, but would never provide sufficient, convincing proof for those who need it, be they good believers trying to convince nonbelievers, or nonbelievers who just re quire that touch of the miraculous and supernatural, hence damning multitudes of justified non-believers to fry for his amusement.
Waaaaaait... I'm supposed to be playing a game of hypothesis... but this is SUUUURE sounding alot like modern times...

Okay, you wooden-headed believers in a god that can't exist by the idiotic pipedreamed powers and standards you purport, it's time to accept some things.

Your god is NOT omniscient. Confused, senile maybe, but doesn't know it all.
Your god is NOT omnipotent. Crippled and impotent maybe.
Your god is a fucking tyrant.
None of you faithful really know ANYTHING about god. You THINK you do, but you have it all ass backwards, as evidenced by the way reality works. Face it, YOU don't know shit.
God doesn't exist, and you're wasting precious time preparing for a figmented afterlife and letting an otherwise enjoyable life pass you by.