It is not becauqz you put a different tag on something that it becomes distinct.
What and who receive different names because what and who are different concepts.
Then in what way are they distinct? There must be something different about them, but I don’t see what it is. You seem to be violating the LNC here once again. What else does ‘personality’ mean if not intellect, will and substance?
Person, not personality. A person is a who.
Intellect and will are faculties (powers). They are possessed by a person.
Substance is the essential nature of a thing. It is also possessed by a person.
But the person is none of those. Those are part of the “what” of a person. The person is who.
Besides, isn’t God supposed to be ultimately simple and not composed? That’s the Thomist doctrine anyway, but maybe ‘Saint Thomas’ was wrong in this respect. How can an uncomposed being be composed of three different persons?
Probably not a contradiction, just a ‘mystery’ because I am quite sure you are going to claim that God is not really composed but that has to be seen in a different way etc.
When we say God is uncomposed, we mean God cannot be divided. All of God is essential. He has no parts which can be removed from Him. A human without a left arm, or without eyes to exercise the faculty of sight, is still a human; we have parts which are not essential to being a human. A car without a bumper or without a right front tire is still a car; it has parts which are not essential to being a car.
God has no parts because, by logical necessity, the divine substance cannot be broken into pieces. A perfect being cannot have anything removed from it and remain perfect. If something could be taken away from perfection, it would not really be perfection.
God of course has “parts” in the sense that He has intellect, will, substance, etc. He’s not some blob of whatever. But God does not have “parts” in the same sense in which we normally use the word, as bits of a thing which have their own existence which continues if removed from the thing. You can remove a tire from a car and the tire will exist on its own. You can’t remove the divine will from God and have it exist on its own. All “parts” of God are essential and cannot exist outside of God, so it would not be correct to call them parts.
One of the characteristics of the divine substance of God is that it is fully possessed by three persons. God being more than one person is another logical necessity based on how God has revealed Himself to us. If God is eternal and existed before all of creation, then at some point (terms related to time are obviously being used in an analogous sense here), there was nothing but God. That means God, who is love, had nothing to love but God. If God is only one person, then God cannot be love. He would be narcissism. No, if God is love, then God must by logical necessity be more than one person.
All of which is completely beside the point, since you consider yourself to be an atheist and don’t believe in God to begin with. Just as everything we say comes from the presupposition “God exists”, everything you say comes from the presupposition “God does not exist”. As long as you hold to that belief, you will assume anything we say which claims God exists is wrong, and look for whatever excuse you can find to justify your belief that we are wrong. Even if it means doing something like claiming the concepts of what and who are identical concepts.