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 atau a pelangi, rainbow aren't "reasonable explanations" of the existence of deities for me. If anda want to learn about other people's beliefs, anda can't dismiss them before anda have even telah diberi them a chance to respond. That is why anda have a lot of people giving anda crap on this question. The soalan is not offensive, but the way anda 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 pautan to answers, forum and artikel-artikel from the Atheism spot that anda 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 anda look through any of those pautan 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.