During my ministry days, we used to ask potential Sunday School teachers to describe in writing their understanding of the Trinity. The variety of answers we received reminded me of something I heard in college: "If you ask your church members to explain the Trinity, you'll get ten or fifteen incompatible explanations, all of which have been declared heretical by the church."
But that was fine, because all we were looking for was something like: "I believe that there is only one God, and that he exists in three persons: Father, Son, and Holy Spirit." If someone got that much, anything else was gravy.
The problem is: The statement above is a faith statement about the Trinity, but in no way is it an explanation. Rather, it lays out a seeming impossibility, and says: "I believe it." If I heard this for the first time, with no understanding of Christian doctrine, or if I heard a similar statement from someone from another religion, I'd have to ask: "What can that possibly mean? How is that not three gods?"
Nevertheless, the statement above was fine with us, and that's because the Trinity is something that I now think of as a Sunday Truth.
I got the term Sunday Truth from the 20th century philosopher Bertrand Russell. In one of his essays, Russell imagines that a government with enough power could get its people to believe any ridiculous thing, such as that water freezes when it gets hot and boils when it gets cold.
"Of course, even when these beliefs had been generated, people would not put the kettle in the ice-box when they wanted it to boil. That cold makes water boil would be a Sunday truth, sacred and mystical, to be professed in awed tones, but not to be acted on in daily life...any verbal denial of the mystic doctrine would be made illegal, and obstinate heretics would be 'frozen' at the stake. No person who did not enthusiastically accept the official doctrine would be allowed to teach or to have any position of power. Only the very highest officials, in their cups, would whisper to each other what rubbish it all is; then they would laugh and drink again." - Essays in Skepticism, pt. 2, Intellectual Rubbish
Even as a minister, I realized that we didn't expect anyone to be able to understand or explain the Trinity. The actual Christian doctrines of the Trinity were hammered out over the first four centuries of the church, in response to conflicting teachings about Jesus that had gained enough traction to be a problem. And the doctrines are complex, confusing, and hard to follow. Check out Wikipedia's entry on the Trinity and see how long you can keep reading. 😎
Not only that, but every explanation I learned in Sunday School as a child turned out to be heretical. One teacher told us, "Just as a woman can be a mom, a sister, a daughter, a wife, even though she is still one person..." Nope, that's modalism (which says that God is one being who relates to creation in three ways), condemned as a heresy in the 400s.
Another teacher said: "Your body has a heart and lungs and kidneys but it's one body..." Nope, that's partialism (which sees father, son and spirit are each part of God, but only fully God when combined), condemned as heresy in the 600s.
Mostly when people talk about the members of the trinity, they seem to slip into tritheism (which says there are three gods who work together, a divine Justice League). I once heard a preacher describe God (the father) thinking about whether to create the world, and then the preacher added: "Then God turned to Jesus and said, 'You know that if we do this thing, you're gonna have to go down there and die for their sins!"
Explanations like these are common because they actually make sense. The "orthodox" explanation (which, though based on various Bible passages, took centuries to hammer out) does not.
I recently rediscovered a favorite quote from Thomas Jefferson from an 1822 letter. He sets up the favorite quote by writing that "the Athanasian* paradox that one is three, and three but one, is so incomprehensible to the human mind, that no candid man can say he has any idea of it, and how can he believe what presents no idea? He who thinks he does, only deceives himself."
I think that few Christians would claim to understand the Trinity. Yet they swear that they believe it, adding that it's a "divine mystery", and that "God's thoughts are higher than ours." It's a Sunday Truth, after all.
I used to think that too, and I didn't see the harm. But that leads me to the quote I mentioned. Continuing on about the one who claims to understand the Trinity, Jefferson says:
"He proves, also, that man, once surrendering his reason, has no remaining guard against absurdities the most monstrous, and like a ship without a rudder, is the sport of every wind. With such persons gullibility which they call faith, takes the helm from the hand of reason, and the mind becomes a wreck."
Jefferson might have added something well-known in the early days of the Republic, and increasingly apparent today: When such persons take the helm of government, the nation becomes a wreck too.
*Refers to the Athanasian Creed which, 300 years after Jesus, defined the orthodox understanding of the Trinity.