My main approach to explaining atheism is not to deny God but, rather, to deny any knowledge about the supernatural -- and I think we can all agree that God is as supernatural as it gets.
A common response to the above assertion goes something like, "What IS the supernatural, anyway?", or "That depends on what you mean by supernatural".
So let's clearly delineate the difference between the natural and supernatural realms.
The natural realm is the entire universe and everything in it; including Earth and life. The supernatural realm is, by definition, outside the natural realm -- so there's NO evidence for it, NO contact with it, and NO knowledge of it. Any claim to the contrary is an insult to intelligence. Period.
Please note that I'm not claiming God does not exist . . . I'm claiming nobody knows anything about him (including whether or not he exists). Nobody knows what he thinks or plans, likes or dislikes, does or doesn't do.
Some believers might retort that we don't need direct knowledge of God because we have divinely inspired scripture from God. Of course, that's recursive reasoning; circular logic. If scripture is one's source of faith because it's divinely inspired, then one must presume God exists to inspire it in the first place. Maybe with all that circular logic, believers are too dizzy to think straight.
To put it in one sentence -- Denial is part and parcel of the suspension of disbelief required to accept the physically impossible claims and stories of scripture. When we deny reality, it has a way of coming back to bite us on the butt. Turn on CNN world news (anytime) and, within 30 minutes, you'll see plenty of consequences for denial. In fact, it can be fairly asserted that the Abrahamic religions have been THE most persistently divisive influence in the history of mankind.
We often hear from moderates that the zealots who destroy and kill in God's name aren't really "true" Christians or Muslims. How can anybody know that? Moderate believers are moderate because they cherry-pick the verses they observe and follow. They're selective believers. After all, nobody but those whacky fundamentalists really expects them to follow scripture absolutely -- do they? That would be crazy!
The truth is, you can't adhere faithfully to scripture because scripture contradicts itself and is not always to be taken literally. Fundamentalists won't admit this and cling tenaciously to the simple-minded proposition that they must believe and obey every word of scripture. It's God's word or it isn't. Which means God must smile on the zealots. They may not follow every word but they try; they believe. Surely God must like such earnest fundamentalism better than the presumptuous censoring and implied criticism of selective "moderates".
Let's face it, the Old Testament and Qur'an reveal warrior Gods who kill with vengeance and without remorse. The depths of sadistic depravity contained in these 2 scripture are not reconcilable with a loving, wise and timeless, God. Why the hell are there so many atrocious acts in "holy" scripture? One has to wonder what kind of God would divinely inspire scripture like that. Suspension of disbelief -- willful ignorance -- is a definite requirement of faith.
Having said all that, I must confess that most of my friends are religious. My wife is a devout Catholic. I don't care if you're a faithful believer as long as you're honest about it. If you claim faith because you want or need God, then I say "Amen". If you claim faith because you know which God is the real one and you know what he likes and dislikes, then I say get the hell away from me! Don't come to me, uninvited, pretending to know what you can't possibly know.
Those who profess their faith honestly admit it is a subjective, personal, choice and without basis in logic or evidence. They don't claim a rational explanation for supernatural claims and they don't presume to claim knowledge of God's mind. They're not in denial. It's the ones who do make such claims who are being dishonest. They are in denial. Their rationalizations are a house of cards.
Therein lies the crux of the problem. Denial leads to belief systems built upon dishonesty. Certainty is a facade masking a web of delusions -- claims of knowledge nobody can possibly possess. Whereas "honest" believers recognize the subjective, personal nature of their faith, "dishonest" believers do not. They are threatened by disbelief and respond angrily when their faith is challenged. If only all believers could admit that they believe for subjective, personal, reasons -- and not objective, rational, reasons -- then religion would finally become the personal preference that it really is. Fundamentalism would evaporate and zealotry would fade away. There would be nothing (religious) to fight about any more.
Imagine that: a world without religious strife . . . wouldn't that be nice?
You love his song - now recall John Lennon's lyrics:
Imagine there's no Heaven
It's easy if you try
No hell below us
Above us only sky
Imagine all the people
Living for today
Imagine there's no country
It isn't hard to do
Nothing to kill or die for
And no religion too
Imagine all the people
Living life in peace
You may say I'm a dreamer
But I'm not the only one
I hope someday you'll join us
And the world will be as one