However, this really raises the most hair-raising question: if God wasn't necessary to cause identity, then we have at least one non-God thing that exists independently of God's creation that even theists must logically admit given the argument is sound. There goes theistic arguments that God is necessary to explain any non-God existence at all! While it doesn't follow from the argument, it does set the stage for the question: why should we assume the existence of the material universe must be explained as "created" or "beginning" in the first place?
You decide.
------------------------
EDIT: Oh yeah, PS. I forgot to mention that this argument also undercuts the basis for the Transcendental Argument for the Existence of God. Whoops! Tiny oversight.
I think it is time to reprise the Transcendental Argument for the Existence of God:
Logic presupposes God, therefore all arguments against his existence are fallacious
With or without belief in God we must agree that there are, or there are not, principles known as the laws of thought. To propose a transcendental argument as an acceptable logical method to argue from experience to the existence of God is to confirm the laws of thought as unequivocally correct. God must be assumed in order to make the argument, and to do that we must call upon logic. So of course God must be logically possible for believers, and if the concept is logically possible then God is subject to the laws of thought.
Transcendental arguments are anti-sceptical and inform us that some form of experience must be assumed in order to argue against experience. On that basis it must be accepted that there is something rather than nothing. The question, then, is what is true of the something? We may begin with Descartes Cogito, correctly modified: There is thinking. But from There is thinking it doesnt follow that whatever is thought is true when nothing in the external world is demonstrably certain. The universe exists, we say, and yet it can be conceived as non-existent (The Problem of Induction); and the universe, therefore, as with any other element of the contingent world, has no necessary existence. Therefore the only certain truths are those that are self-evident. So if God exists were a certain truth then of course a direct contradiction would be involved if denied. The concept of God is that of an Absolutely Necessary Being, a personal deity that causes and sustains all existence and cannot fail to exist, and yet the non-existence of such a supernatural being is a proposition as clear and distinct in the understanding just as it is for any contingent thing that can be conceived not to exist. Hume and Descartes, empiricist and religious sceptic on one side, and rationalist and believer on the other, both identified the impossibility of supposing any necessity in an object always remaining in existence: God cannot be demonstrated a priori.
And crucially, if the argument is that God is the cause of logic then it follows that God is outside logic, and if God is outside logic then no argument to God can be made since the argument wants to say God is logically possible. And on that account the argument doesnt even get out the starting gate.
We can conclude if, according to TAG, logic presupposes the existence of God then it is a demonstrably empty or meaningless presupposition.