I suppose I would have to be called an atheist. There are several things about religion that simply robs me the wrong way. Note that I'm not trying to attack anyone beliefs here, what I'm doing is explain why I'm not a believer. Everyone is free to believe what they want and be what they want as long as they keep to themselves and don't hurt anyone in the process.
First of, I'm not very fond of the idea of submitting myself to something that may or may not be. Some people might say "Are you going to bet on that cold shoulder of pride that your not going to be judged?" The answer is simple - Yes I am. I have yet to see anything that would indicate the presence of an all power full being, watching me. If a god is proven, I will submit to him no doubt, but as things are now, I have yet to be convinced. Some people may say "I experience God on a daily basis", well I don't, and someone elses personal, spiritual experiences is not very persuasive. I could not convince a religious person to become an atheist by saying I don't experience God.
Secondly (this one is about creationism), the evidence in support of evolution. Almost every field of science have in one way or another supported the theory of evolution, be it genetics (HUGE support), fossils, geology, chemistry etc. Many of the arguments against these are quite often just false, like there are no transitional fossils. That's just not true, there are tons, hundreds even, yet some people still exist that they simply don't exist. I can name one right off the bat; Tiktaalik (google it). Also, the "counter part" to evolution, Intelligent Design, is a joke! The entire premise behind it is based on a negative argument. It has no real evidence, what it does is to "pray" on the gaps in the theory of evolution. I'd hardly call that a scientific theory, and neither did the American court. I could go on, but I'll just direct you to these YouTube profiles: http://www.youtube.com/user/Thunderf00t
Thirdly, there are so many religions and I have yet to see one make more sense than any other. If there was one supreme being that was addressed in all religions, all the scriptures would point in the same direction, which they clearly don't. If there is one right religion, how can we be sure which one is the real one? If you look at the world from their prospective, they all seem like they are the one, so what would point to one religion over another?
Fourth, the problem with evil. Supposedly God is all power full, all good and all knowing. So how can evil exist? If he wants to stop evil but can't, he is powerless. If he can stop evil but doesn't want to, he is wicked. If he can and want to stop it, how can evil and pain still exist? Some might say that pin exist to remind of that we are not happy or don't feel comfortable, but couldn't we just indicate that with less pleasure? Not to the degree where we suffer, just so that we understand like something is wrong.
Finally, I'm not fond of anything that actively hates certain kinds of people. This is only for the extremists, but still, be it people hating homosexuals, black people (claiming the bear the Mark of Kain), people of other religion, anyone who is not of their specific culture, whatever, I will not accept these kinds of intolerants. And this goes for anyone, including atheists who harass religious people, no such harassment is OK, no matter who does it.
Again, I'm not here to insult anybody, these are just things the way I see it. If you have found the truth (if there is such a thing) in religion, that's great! All I ask is that you don't try to force this truth onto everyone else. If we think your version of the truth is the most plausible, we'll come to you.