I'm an atheist, not because of a rejection of a deity or of religion, but because I don't believe in a higher power and never have, despite having received a religious upbringing. I never had faith, but I always had logic.
I choose to embrace a different faith and take the position that creation logically implies a creator. We live in a universe that demonstrates cause and effect and this alone strongly supports belief in God over a creation of random happenstance.
I don't pretend to know how the universe started, if there was even a start. This is a very difficult scientific problem, experimentation is not very useful, at least not with our current capabilities. I don't see any logical way to go from there to the existence of a god. In fact, the existence of a god doesn't even solve the problem, because the question simply becomes, how did that god start/appear/was created ?
As
CoinCube said, there is no logic in thinking that this universe could ever come about without a maker. Why couldn't it? Because of the complexity.
Nowhere in the universe where we have examples of complexity, that we understand the source of, where the source is ever less complex than the result. Even so, the whole universe had a source that was way more complex than it is. And since there is intelligence, emotion, identity, spirit, etc., in the universe, the source must have these things within itself, as well.
The logic is God.
