In 325 AD, the Council of Nicea declared that God was a Trinity, three separate and distinct Persons who nevertheless were one God. The history of this declaration, both before and after the Council, makes for some interesting reading. For example, Saint Athanasius is remembered for being the leader of the fight against the heretic Arius and for being the chief architect of the doctrine of the Trinity. These two accomplishments were the main reason Athanasius was later canonized, and you’d think they’d have been enough to make him forever admired in the Church.
But he wasn’t. Saint Eusebius, for one, used his political influence to get Saint Athanasius exiled twice, the latter occasion resulting in Athanasius’s death. Despite Saint Athanasius’s great success at Nicea, Saint Eusebius was deeply suspicious of Athanasius’s theology, and wanted him out of the picture. Trinitarianism was not the answer the church was really looking for, and council after council found itself picking up the issue of God’s nature, and Christ’s nature, and trying to resolve the issues raised by the previous “solutions.”
The problem is that the Trinity is essentially a self-contradiction at heart. Christianity drew its theological roots from the monotheistic traditions of the Pharisees, and felt very strongly that there was and could be only one God. At the same time, there was an equally strong movement within the Church to regard Jesus as a divine being Himself, separate and distinct from the Father, but equal in deity. Obviously, adding a second God would be a radical change from past traditions, so those who supported the deity of Christ found themselves a Scriptural precedent: the Holy Spirit, who God sometimes referred to in the third person. If the Holy Spirit could be a deity distinct from the Father, then Jesus could too.
But wait: how does adding another deity resolve the conflict with monotheism? Answer: it doesn’t. All sorts of “explanations” have been proposed, and each one has been branded a heresy by some Church council or another. In the end, the councils decided that the Trinity was a “mystery”–a riddle that human wisdom was too limited to solve, and that mankind could never untangle. Or in plain English, the Church realized that there was no way to resolve this inconsistency, and so they just gave up.
The problem is that if you have three distinct Persons, each of whom is God, then there is no meaningful difference between your theology and polytheism. Polytheism is also a belief in multiple persons, each of whom is God. If you say Trinitarianism is not polytheism, all you’ve really done is to create a new label for belief in multiple divine persons, and made the arbitrary declaration that your theology falls under the Trinitarian label rather than the polytheistic label. It’s purely a marketing and branding issue. The products are the same.
Even Christians find this inconsistency to be troubling, and have tried a number of ways to get around it. The problem is that no matter what solution you propose, there’s something even more heretical about the solution than there is about the original problem. For example, you could propose that deity is a kind of nature, or substance, that can be shared by more than one person, just as “humanity” is a quality shared by all humans. The problem with this solution, however, is that this is even more frankly polytheistic than the Trinitarian formula: different gods are all divine in exactly the same way as different men are all human. If this were the answer, then the Father, Son, and Holy Spirit would be three distinct gods, just as Washington, Jefferson, and Franklin are three distinct men. This answer is heretical because it makes monotheism a false doctrine.
Or there’s the idea that the Father, Son, and Holy Spirit are simply different forms or modes which God assumes in the course of going about His business. Just as water can be frozen to produce ice, or boiled to produce steam, God can “condense” Himself into a mode that allows Him to appear in the flesh as the Son, or “evaporate” Himself to spread Himself through the world as the Holy Spirit. This doctrine, known as “modalism,” has many theological problems and was long ago declared a heresy by the Councils. If modalism were true, for instance, then the Son could not submit Himself to the Father’s will, because the Son is the Father, in a different mode. Modalism preserves monotheism by abandoning the idea that the Father, Son and Spirit are distinct persons. Jesus was just a hand-puppet being manipulated by God, not a real person interacting with God. But if Jesus was not a real person, then his “sacrifice” was a sham, a charade, worthless, and the Gospel is a fraud.
There are other examples, of course, but in general, you can pretty much take it for granted that if someone claims to have “solved” the Trinity, then whatever answer they give you is going to turn out to be a doctrine that the Councils have already declared to be heretical. The Trinity is a “mystery” precisely because you cannot remove the self-contradiction without destroying the doctrine itself. And as I’ve pointed out elsewhere, this is the hallmark of an untrue tale. God does not show up in the real world. We are not looking at God and puzzling over His mysterious nature. We’re not dealing with a real-world deity here. All we’ve got are the stories of men, and those stories contradict themselves.