There's a saying by Reinhold Niebuhr known as the "Serenity Prayer." It says "God grant me the serenity to accept the things I cannot change, the courage to change the things I can, and the wisdom to know the difference".
A discussion in the forums made me realize something today: For a Christian, the above is impossible, or nearly so. That's why they think the prayer is so important that they post it on knick-knacks all over their houses. They want their god to grant these things to them, but because they really think that by praying they should be able to change those things that are beyond their control, they will never have that serenity.
But as an atheist, this is easy! Once I realized that there was no such thing as Yahweh or any other god, I actually gained that peace that is beyond the Christian's understanding. I know for a fact that there are some things I can change, and some that I can't, and so accepting the things I cannot change becomes easy.
There are many things that Christianity claims for itself that are merely wishful thinking. The "peace that passes understanding" is once. Another important one is "ye shall know the truth and the truth shall make you free." These are things that only the atheist can enjoy.