How does atheist know they are correct?

People aren't saying that The Big Bang Theory is 100% true, but it's the closest thing we have now. Maybe we will find evidence that proves something else. Scientists are constantly looking for evidence and proof and science grows every day. Science concentrates on finding knowledge and understanding the world. And the big bang theory is the theory how the universe came to be and not the world. Your question should beasked about god and how he came to be and so on. Atheist don't have faith they have factual evidence for their position and while religion makes you live in the 14th century. Look at what science have given you and then look at religion who live in a fantasy world where the only thing you have to do is pray for your problems instead of dealing with it yourself. What do you want to believe? An ancient text from primitive homosapiens or something accurate and sane. Look up Ray Comfort or Kirk Cameron on youtube and watch the videos where people explain why they are stupid liars. I can also recommend Thunderf00t's "Why people laugh at creationists", or "The Amazing Atheist" & "JacklynGlenn" & "The Atheist Experience" and others you can find :)