A common error is to assume that if everything has been created by something else, then something other than GOD created GOD. This error indicates a lack of understanding of the argument since the argument is based on the assumption that not everything has a reason.
Still, there must be one first reason why there is no reason, and that is called GOD. Here the question arises: if there are things that have no reason, why is there a need for GOD as the reason without reason, instead of assuming that it is the universe itself? Why not believe that the universe has always existed in one form or another, without requiring another more fundamental reason for its existence?
The argument of first cause, or first reason, is that things can just exist with no reason. GOD has no cause; he just exists. But now, a new question arises in the question of whether there is a god. Why do we assume it is a god and not just the universe?