God is a Trinity. He is 3 divine persons in 1 God.
Of course, we have Unitarian Universalists who preach differently, as well as JWs who do not believe Christ is the Son of God, and we have Muslims who do not accept Christ as other than a prophet, and we have Jews who do not believe in Christ as a Messiah.
Now all the ‘discussions’ from the groups who do not hold to the doctrine of the Trinity do not make the doctrine of the Trinity "Debateable’ according to the Catholic faith, do they?
We have definitive Church teaching that the Trinity is what the Trinity is. . .that is that.
Of course, you can go all over the boards and find all sorts of discussion from Muslims and Jews, and from JWs and from UUs, that denies that doctrine.
It doesn’t mean the doctrine is ‘up for discussion’–even if many disagree. Even if we Catholics still have to come on and say, “No, I’m sorry, but you are incorrect. The Trinity is Truth”.
Funny how other equally authoritative doctrines are ‘assumed’ to be ‘changeable’ simply because people come on and say, "I think we should do it’ and other people have to come on and say, “Well, you might think so but Catholic teaching says it cannot be done. . just as Catholic Teaching says the Trinity is Truth, and not Unitarian Universalism, JW, or even Muslim or Jewish belief. . .”