In my opinion, your post has completely missed the point of these beliefs. The Trinity and Original Sin are names for doctrines, much like “5-Point Calvinism” describes a particular interpretation of the Bible. The fact that the exact phrasing is not used in the Bible is irrelevant to their veracity, because the names themselves are just shorthand used for describing the position itself. (Similarly, just because the bible doesn’t use the exact phrasing used by philosophers to describe “free will” says nothing about whether it says humans have it or not.)
You have implied in later posts that the Trinity implies there are “three gods.” This is actually a serious Heresy to all Christian denominations – and is considered so serious that those few churches (namely the Mormons) who hold to said beliefs are considered no longer Christian. The doctrine of the Trinity is easily defined by seven bullet points, all of which were subscribed to by the early Christians and pretty clearly proclaimed in the Bible. If the bullet points are true, Trinitarian belief is true.
- God is one.
- God the Father is God.
- God the Son is God.
- The Holy Spirit is God.
- The Father is not the Son.
- The Son is not the Spirit.
- The Spirit is not the Father.
As to why we believe the above points:
- You already believe this as do all Monotheistic religions.
2-4) History and the Bible are pretty clear on the fact that the earliest Christians proclaimed all three to be God and worshipped all of them as the same God. Jesus Himself makes so many claims to be God that the Jews up and executed Him for it.
5-7) These follow from the fact that the three aspects are not shown as identical in all respects. They are pretty clearly carrying out different roles and, in some cases, are not even accessing all the information or power they have at their disposal (purposefully limiting themselves).
In conclusion, we believe in one God in three persons. None could exist without the other, because they are all the same being and to not have one would be to not have the others as well. Yes it is complicated, but no one should expect God to be simple for our convenience. He is what He is. If you want to know how this works, read a philosopher.
Tradition merely proclaims the obvious fact that all Christians have to believe in this because – unsurprisingly – it is rather important info! No council proclaimed any of points 1-7 on its own; all were taught clearly in the Bible and do not require any esoteric reading to get to (indeed, in my experience, there is usually a lot more twisting from Jehovah Witness and Mormons trying to get *out *of believing in it.) So whether Tradition stands above the Bible is in this case irrelevant. Tradition merely defined what doctrine Christians had to subscribe to before we kicked them out for heresy (because there *are *points where you can be wrong and still a Christian)-- it did not make up any part of the doctrine itself except the name. So the point is moot.