>I suppose for those who consciously or subconsciously know they're guilty of sin, the idea of annihilation is far preferable to facing judgment for their sins in the past, so I can see how atheism would be an attractive option, ultimate meaninglessness notwithstanding. But Christianity is primarily about what to do with that guilt -- that God's son Jesus paid the price for your sin and mine, and he offers forgiveness to those who will trust him and call on his name. (And I'm sure you've heard that before.)
Your comment and a lot of others seem to presuppose that atheists don't genuinely not believe in God, there must be some sort of rejection of a God that exists or some conscious/unconscious attempt to avoid taking responsibility for something.
My not being a Christian is really simple. It has nothing to do with my ideas on the bible or morality in general. nothing to do with whether or not I'm a sinner (I agree with you and Christianity that everyone falls very short of moral perfection), it has nothing to do with my personal happiness or making it easier for me to sleep at night.
I simply don't believe that supernatural events exist. Nothing I have heard, discussed, read, watched or experienced in my life has convinced me that supernatural things happen in a general sense or that the specific supernatural things that are essential to believing in Christianity have happened.