Christians often get frustrated with atheists. They complain that no argument is good enough, that we must be even more dogmatic in our unbelief than they are in their belief. You see this whine reflected in the swiftness with which believers, desperate to refute Dawkins and the "new atheists," began referring to them as "atheist fundamentalists." Nothing they can possibly say to persuade these closed-minded heathens will ever change their minds.
What believers don't see is that this has nothing to do with the presumed intellectual constipation of atheists, and everything to do with the lame quality of their arguments for faith. You must realize that to a lot of believers — not just the rank-and-file Jack and Jill Churchgoer, but even to apologists who write books and ought to know better, like Ray Comfort and Dinesh D'Souza — laughable nonsense like Pascal's Wager or Lewis's "lord, liar or lunatic" are excellent arguments. The simple fact is that, to an atheist who has spent years living his/her life rooted in reason, the feeble, emotionally comforting justifications that believers use to prop up their beliefs won't work.
So what can believers do to change our minds? Often I've been asked, "What would it take to convince you? What evidence would break through your intellectual front lines?" Maybe you've been asked this yourself.
My response is to tell the believer that they should be directing their question at themselves and not me. Here's what they should do.
Ask yourself, "Why do I believe in God?" Be brutally honest in your answer. Do you believe simply because you've been raised to believe and have never thought to question your upbringing? Or do you think you actually have sound intellectual reasons for your theism?
If you answer in the former, then you need to ask yourself if that is really good enough. Believers like to throw around terms like "intellectual honesty," so any believer who is willing to admit they hold on to their theism simply because they were raised Christian ought to ask themselves if it is truly intellectually honest not to question beliefs just because you were raised in them.
If you answer in the latter, then ask yourself this: If your reasons for belief are intellectually satisfying to you, and are in your opinion well supported by evidence, then are those reasons on their own strong enough to sway unbelievers? If you think of yourself as a smart person, and your reasons to believe were strong enough to sway you, shouldn't they be good enough for anyone else also?
If yes, then by all means, present them. And expect them to be scrutinized and evaluated. Don't be angry if they aren't just automatically accepted.
But if you don't think your reasons are strong enough to sway an atheist, then ask yourself, why did they sway you? Are they really especially good reasons? Or did you allow something else — your emotions, your desire for acceptance and fear of rejection by your neighbors and family — to overpower your reason? If other smart people aren't convinced by your reasons, should you have accepted those reasons as good enough for you, being that you're a smart person too?
So don't let atheists' insistence on arguing these things down to the bone frustrate you, and don't waste time asking us what would convince us, because that effectively amounts to your giving up. (And if you're doing that, what does it say about how supportable your beliefs are?) Instead, take a moment to really evaluate your reasons for being a believer, and be coldly, unforgivingly honest with yourself in that evaluation. It will be difficult, but it's worth doing. In my case, I must admit it was that process of self-evaluation that steered me towards my eventual atheism. But if such self-scrutiny only reassures you your reasons are sound, and that they are sound enough to trounce all of us "new atheists," then bring 'em on. And prepare to defend yourself in a hearty argument. Much as people might like to think of us as "atheist fundamentalists" as an excuse to avoid getting in such arguments with us, just remember, we aren't fundamentalists, we're rationalists who insist on strict fidelity to evidence and reason. If we can be proven wrong, we'll admit it when we are.