In most cases, atheism is an emotional response to hurt or tragedy in life, the result of the age-old question, if there was a God, why does he allow bad things to happen.
They want to believe that there is no God and in the effort they do an intellectual suicide. In reality, if we are intellectually honest, it doesn't take much to come to a plausible conclusion that there is a creator. Things doesn't just pop out into existence merely by chance.
Newton's first law of thermodynamics still stands - matter and energy cannot be created or destroyed (we can only change one form of matter into another form and one form of energy into another form). So it is quiet safe to assume that someone who can violate the physical laws has to create the original matter and energy.