Goldwing, you have stuck your reply inside my quote, so I can't quote you without looking as though I'm quoting myself.
What you asked was, "That christians have debated the Trinity over centuries does not diminish it's truthfulness. Can you name a doctrine in which Christianity has been in agreement since the death of Christ?"
Well, the Resurrection might be one such doctrine.
The fact is, the Trinity is not clearly set forth in the NT. The debates that raged for centuries were
not, "What is the Trinity and how does it work?" The debates
were, "How can Jesus have been both human and divine?"
The Council of Nicea was largely a response to Arianism, which is basically what the JW believe. Jesus is the Son of God, but as the firstborn of creation rather than the Second Person of a Trinity. Before the doctrine of the Trinity had been adopted, there had been intense negotiation, political intrigue, deaths and even a brief flip-flop back to Arianism as the official position.
So it's not as though it took centuries and all the brouhaha to reach agreement on something like the Virgin Birth or the Resurrection, which are clearly stated in the Bible.
You're correct - the Trinity is either true or not, and whether anyone agrees with it won't make it more true or less true. I can see the Trinitarian perspective as well as the non-Trinitarian perspective. Even for those who fully accept it, however, it's not clear to me that it adds much except confusion. If it's an article of your faith, I certainly wouldn't try to talk you out of it.