God is eternal. He has no beginning and no end. This is foundational for a popular argument for God’s existence. Reason demonstrates that something must have always existed.
It is not possible to count to the end of the series of real numbers. We can always count one more. It is, in one sense, an infinite series of discrete things. We can’t count to the end of a string like that. It has no end. An unending series of discrete things cannot, after all, have an end.
Similarly, we cannot expect that an infinite regress of finite causes exists either. That is, if we move backward from ourselves to the things that caused us, then backward to the things that caused them and so on, we must find something that did not have a beginning. Otherwise, the unending series of causes would have never arrived at us.
The infinite regression cannot exist in reality. Whatever the first cause was, it must have always been and it must have the power and ability to bring about all we see in the universe.
Something, or someone, has always been here. It was not caused to be by something that existed before it. It is self-existent; it has the power of being in itself because it existed by itself before it created.
As J. P. Morland points out, nothing outside this first cause can cause it to either act or not act. At the beginning, there was nothing outside it, so there was nothing to cause its actions. It has the power of choice. Only a person can choose to act or not to act.
This personality has always existed, is powerful enough to create the universe, and displays intention. This fits the Christian notion of God quite well, but not perfectly. But it must be kept in mind that this is not the only argument that can be given (Please see search label teleological argument," amoung others.).
Theistic arguments cannot be taken in isolation. We cannot ignore the things that one sub-argument proves just because it does not by itself prove the whole.
Counter-arguments often given revolve around the nature of time itself. Please note that I have not referenced time except as a reference to the string of causes, a reference to the order. I believe that time is an abstraction in the strictest sense.
The only way we measure time is by looking at some physical entity that is changing. It changes almost constantly in reference to everything else. A ticking watch and / or a decaying radioactive element is something that change physically. Time is our way of coming to terms with the change all around us, our way of referencing the changes we cannot keep track of.
We could think of it like a statistician does. We often look at experimental in “time order” so we can get an idea of any unknown independent variables that could be influencing the experimental outcomes. All we really have is a sequence of physical causes. Maybe there is a pattern in that sequence which gives away an unknown factor. Maybe if we keep careful notes, we can guess what it is.
The concept of time helps us to keep our bearings in the sequence of physical beings, but it has no existence in and of itself. Counter-arguments that reference a particular theory of time are just dancing around the obvious.