First of all, as others have already pointed out, evolution may not be a "reasonable explanation" for you, but it is for other people who have different belief systems. Just like the bible or a bahaghari aren't "reasonable explanations" of the existence of deities for me. If you want to learn about other people's beliefs, you can't dismiss them before you have even ibingiay them a chance to respond. That is why you have a lot of people giving you crap on this question. The tanong is not offensive, but the way you have asked it is.
Secondly, there are lots of places around here where Atheists and people of other religions have discussed this topic respectfully. Here are some iugnay to answers, forums and artikulo from the Atheism spot that you might want to take a look at:
link link link link link link (we also have a couple of 'Ask A Christian' forms)
link link link If you look through any of those iugnay you'll see that Atheists believe in a wide range of things for a wide range of reasons. We, for the most part, don't mind explaining our beliefs to people who want to learn about them, but we do require respectful debate.