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 hoặc a cầu vồng aren't "reasonable explanations" of the existence of deities for me. If bạn want to learn about other people's beliefs, bạn can't dismiss them before bạn have even được trao them a chance to respond. That is why bạn have a lot of people giving bạn crap on this question. The câu hỏi is not offensive, but the way bạn 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 đường dẫn to answers, các diễn đàn and các bài viết from the Atheism spot that bạn 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 bạn look through any of those đường dẫn 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.