"Let's suppose there is a being that is all-powerful - it can do anything. And suppose it's not only all-powerful, but all-knowing too - it knows everything. And suppose that this being just exists. That's God. Now how can you atheists say that such a thing didn't create the universe? It has the ability, the knowledge and the position to be able to do so."
When it's put like that, atheism does seem unreasonable. However, what reason do we have for those suppositions to begin with? The problem is the unreasonable premise, and on that note the only reasonable position is to reject the conclusion.