I'm a staunch atheist. I'm very proud of my beliefs, as much as I'm sure many religious folk are. I, like others, believe to be an atheist, you need to have critical thinking skills and realism in the face of fear (of death, or no afterlife).
I say this because it would be lovely to have an all-powerful god that will reunite me with my loved ones after I die, there to be no more pain and suffering, just peace & happiness. It is a lovely dream, and all anybody can hope for after what can often be, for most, a difficult life. I would absolutely love it, if this were the case. However, despite my wish for it to be true, I know it's not, and have to accept this reality despite the fact that it's a very sad fact, and that I'd rather it not be the case. People will generally believe what they want to believe, it's very easy to do. It's a lot more difficult, I feel, to believe in something you don't want, or wish, wasn't the case.
Having said this, even if I were agnostic, I do have to say that as far as Christianity and similar goes, that if I believed there might be a god (but didn't know either way), I'd genuinely want absolutely nothing to do with them. Stephen Fry sums it up nicely, along with Richard Dawkins (Ricky Gervais also has good points on the topic). I was raised by an atheist father and a Christian mother. I believe I was around age 8 when I told 'god' I hated him and despised him, after watching the suffering my mother went through for several years, that was completely undeserved. I remember at a christian camp when I was young, having the folk running the camp preach that god was perfect. I questioned how this could be the case, given that god 'murdered so many people with a flood', what was happening to my mother, and the suffering of so many others also. The answer wasn't satisfactory.
I'm afraid I do have beliefs that atheists tend to be more intelligent, and that the more religious you are, the less intelligent you tend to be. I'm genuinely sorry if that hurts anyone, as I know it's not a nice belief. It does not mean I'm correct and could just as easily be an unpleasant aspect to my personality.
There are some interesting points on this thread that have given me pause for thought. The agnostic being more intelligent than atheists is an interesting one for me to ponder. My immediate feeling is they may well have a point here.
To touch on the point that plenty of intelligent people do have faith. I'd quesiton this though, how is their intelligence measured? What was their upbringing? I know scientists whom believe in god, which to me, was unfathomable. Until you learn their upbringing was by heavily religious parents. Hard to shake off early life experiences. I know this won't be the situation in all cases though.