The doctrines of the Trinity and Incarnation are often taken to be complicated metaphysical speculations when that is not their purpose. They are primarily meant to describe the way language works in the OT and NT scriptures. This is a text-based approach that the early Fathers used. Creeds are not quasi-philosophical doctrines (modern theologians regularly make this mistake), but rather descriptions of rules of speech found in an authoritative text.
For example, as I was rather ineptly trying to say in previous posts on the Incarnation, human actions are predicated of a divine subject in the Gospels: "The Word [divine subject] became flesh and dwelt among us [human action predicated]" (John 1:14). Some might protest that this is impossible on a priori logical grounds, but there it is in a sentence. Sorry for getting technical here for a minute--I'm thinking in print--but a logical impossibility would be, say, that A is not-A, which violates the law of non-contradiction. This kind of contradiction cannot be expressed truthfully in a sentence: "Jeff is not Jeff" cannot refer to anyone at all. Neither can this happen in reality: "Jeff simultaneously did and did not eat a sandwich." The sentences themselves have proper grammar, but they cannot possibly refer to anything in the world. So the question for John 1:14 is whether, admitting that the language is grammatical, is this sentence like "Jeff is not Jeff," or "Jeff simultaneously did and did not eat a sandwich"? Clearly it is not saying anything like "The Word is not the Word," so there's no resemblance there. Neither is it saying "The Word simultaneously did and did not become flesh and dwell among us." So there seems to be no grammatical or logical contradiction in the verse that might prevent it from referring to something in the world. The sentence is meaningful. The only question then is whether it is true or not. The Creed of course assumes this, but its job is not just to assert truth--the Bible already does that--the job of a Creed is to accurately sum up the way Biblical language works so that we don't talk in a way that contradicts the Bible. Creeds do more than make claims about what God is and is not like. Again, the Bible already does that. Creeds primarily regulate our language.
So the doctrines of the Trinity and Incarnation as they have classically been articulated in the Nicene and Chalcedonian Creeds are, firstly, descriptions of the grammar of Scripture, and it is asserted that that grammar is normative for our speech about God. Secondarily they are an assertion of the truthfulness of that speech, they are an assertion "that" God is the Father of Jesus Christ who himself is of one nature with the Father. Where people get confused is that, thirdly, they think these doctrines are or ought to be understood as metaphysical explanations about "how" it can be that the Father begets a Son or how the Word is Incarnate. But this third use of Creeds is illegitimate. Indeed, the Creeds are bound to disappoint in this regard because they are not designed to answer the "how" question. The most we can say about God is "that" he exists, "that" he has such and such a name, "that" he has done such and such, "that" he has revealed himself in such and such a way, and that we "ought to" regulate our language in accordance with that revelation. We cannot say "how" it is that God has the characteristics that he has, because that would subordinate God to a more primordial explanation than he himself is. God, being the First Cause, is self-explanatory. To explain "how" God is the way he is violates this and turns him into a penultimate cause. So all explanations that attempt to explain "how" God is Trinity are off base, because God, as Muslims and Jews will agree, is self-explanatory. So Christians are not capable and are not permitted to explain the Trinity for reasons, I think, Muslims and Jews would admit. What we can do is (1) proclaim "that" God truly is what the Bible says he is, (2)describe how language is used in Scripture, (3) show that the language of, say, John 1:14 is not ungrammatical, and state that we "ought" to talk about God in this way based on (4) arguments for the Bible being God's revelation. That's it, there's no "how" explanation that a metaphysician might get into.
When asked about the Trinity, it is pretty tempting to give an "explanation" that would distort Christian teaching rather than give a "description" of what that teaching is based on our acceptance of the Bible as God's revelation. We can exercise our reason on why we believe in a particular revelation, but we cannot use reason to explain why and how God is the way he is.