In that case we have an actual Apostle of the Apostolic Church who taught actual error, in scripture no less. Since it took a later consensus of uninspired men to correct his errors, we can conclude that these men were more authoritative than Paul himself, and therefore scripture. You ask us to believe in Apostolic succession, yet you have the students being greater than the master. You ask us to believe that teachings are preserved from teacher to student, yet Christ PERSONALLY taught Paul and you say Paul was wrong and those who followed him knew better. Given your words, how can we possibly have any confidence in Apostolic succession at all?
You CANNOT tell me that future generations kept getting wiser and wiser since you say that you practice the same faith with the same dogma as 2,000 years ago. Your position, therefore, is that at least one Apostle got it wrong, then some very smart men came along and got it right, then no one has improved upon them ever since. To me, that sounds like a Church Father-based faith. The Fathers you agree with were right, and (contradictory) scripture was wrong.
I have yet to fully understand and study the Church's position on St. Paul. I do know that his writings in the Church are not on the same level as the Gospels (when Paul's Epistles are read, the congregation sits; his writings are read by a lay person. The congregation stands when the Gospels are read; the Gospel reading is always done by a priest, and homilies [commentaries] are always made on the Gospels; the Epistles are located in a different part of the church; the Gospels are always on the altar; there is a lot of symbolism in all that).
I only established that (1) it is impossible to find a Trinitarian formula in St. Paul's writings and (2) that he refers to the "spirit of God" in a Judaic manner, as grace, and not as the third Person of the Holy Trinity.
If you want to call it an "inspired omission" or any other rationalization, it doesn't change the facts stated above. Obviously, the apostolic successors did, through divine revelation, establish the dogma of the Holy Trinity from the Holy Scriptures, indirectly. So, their authority in that respect is undisputed as far as I know by mainline Protestants. It is disputed only when it runs against Protestant innovations.