One of my many fans wrote in on this article to offer the following comment, Edited slightly for brevity:

Begging the Question is a logical fallacy that involves already assuming the thing you’re trying to prove to be true, in the lead up to the conclusion of your argument. By labelling God as a “neccessary being” you are putting God’s existence into the definition of God – saying he has to exist. Therefore, you are begging the question. I could do the same with anything. For example, lets say I make a claim about a Wolf King, and the definition of the Wolf King is that he created all wolves. Well, wolves couldn’t have existed if he didn’t, so he is a necessary being, and he must exist. Furthermore, it is never stated why infinite regression is impossible. To clarify, I do not claim to know where the universe came from, but you do. You claim this start point to be God, in other words you claim that the start point is both sentient and aware. You also claim, I assume, that this start point is your specific religion’s start point. To recap, you asserted that infinite regression is impossible, and beyond that you are begging the question by claiming God as a necessary being. Thank you, and I look forward to a response.

And I was delighted to offer the following response.

Sup, Yup?
I am not begging the question, but I understand why it sounds like that. On the surface, it does look like we are saying, “We define God as a being that MUST exist, so obviously a being which MUST exist must exist. Thus, God exists.”

But the reason we define God as a being which MUST exist is not arbitrary, the way authors have tended to define elves as creatures with pointy ears. The necessity of God’s existence is derived, first from his self descriptions. The Bible tells us that God always has been and always will be. We are not forcing into Christianity something which the Bible does not already teach. The only other religion which claims an eternal God outside the Bible is Islam, and I’m not entirely sure about Islam (though it is clear they borrowed much of their ideas of God from the Bible, and the Koran even says so).

Next we can argue back toward that by way of the universe- the universe is time, space, matter, and energy. Nothing can be eternal in the past by ways of consecutive days, and the laws of physics tell us the universe must have had a beginning, and so we know the universe must have come into being.

But from nothing, nothing comes. Something must have CAUSED the universe if it began to exist. What properties must that cause have? Since we are trying to explain the universe, then the cause cannot be time, space, matter, and energy, for that is the thing we are attempting to explain. The cause must be timeless, spaceless, immaterial, amazingly powerful, and highly intelligent (due to the complexity of the universe, the fundamental laws, the fine tuning, and the VAST amounts of information in every field and system, especially living things).

So the universe must have been caused by God because nothing else we know or can imagine fits the description unless we describe God and arbitrarily say “But this is someone else.”

An infinite past or regress is impossible because of what is called the impossibility of transversing the infinite. You cannot add up any number of things until you reach infinity. Nor can you start with infinity and count down until you reach zero. If the past was infinite, then before TODAY could happen, an infinite number of days would have to pass before today occurred. This is impossible. Thus, because today is here, we know the past was finite.

Think of dominoes. Imagine a row of dominoes which contains infinity dominoes. Pick a domino. When will it fall? It will fall just after the one before it falls. When will that one fall? Just after the one before IT falls. Etc. How many dominos have to fall before the one you are looking at falls? An infinite number. How long will that take? Infinity seconds. So when will the domino you are looking at fall? Never. And it does not matter WHICH domino you choose. Move toward the “beginning” by a hundred million billion dominoes. When will THAT domino fall? Nothing has changed because you are still an infinite number of dominoes from the beginning, because there IS no beginning.

Now imagine those dominoes are days, or centuries, or a billion years each. Today will never happen. For today to happen, there must be a FINITE number of days before it. Thus, the past MUST be finite.

The same is true of causes. What caused your domino to fall? The one before it. Why did THAT one fall? Because the one before IT fell. But that cannot go forever into the past. There must be a first domino falling, and it must have been pushed over. The universe is a vast collection of cause and effect relationships, but all of those causes need a FIRST cause. That is God in his act of creation. But what caused GOD? Either there is a true FIRST cause- something that doesn’t need to BE caused, or there is an infinite regress of causes into the infinite past- but as we have seen with the dominoes, that is impossible. Thus, there must be a first cause- an un-caused cause. An unmoved mover. Someone to push over the first domino.

That is God, and he is NECESSARY because there HAS TO BE a first, uncaused cause- a NECESSARY causer of effects. He is necessary because there must be a first, unmoved mover- the hand that pushes over the first domino.

We define God as necessary, not only because He describes himself in those terms, but because He MUST be necessary, or nothing would exist. The argument is as solid as one can be and very old.
I hope this helps.