If all the answers were contained in the Scriptures, why did not Paul do like a good sola apologist and give them a list of Bible verses?
"Now to Him that is of power to stablish you according to MY GOSPEL, and the preaching of Jesus Christ, ACCORDING TO THE REVELATION OF THE MYSTERY WHICH WAS KEPT SECRET SINCE THE WORLD BEGAN, but NOW is made manifest, and BY the SCRIPTURES of the prophets, according to the commandment of the everlasting God, made known to all nations for the obedience of faith." (Rom. 16:25,26).
Paul was given a new message, a message that included salvation by grace through faith, the Church the Body of Christ, the One New Man. These weren't found in scripture. Otherwise, he could have gotten his ministry from Peter and the eleven. This was not of man. Not after man.
We have the scriptures because he was given the revelations.
The scriptures of the prophets that Paul refers to is the death, burial and resurrection of Jesus Christ, found in the Old Testament. But even that is expounded on as new truth: That Christ died FOR OUR SINS, was buried, and rose again the third day.
(Bold added for emphasis, not yelling...;))