Jesus said, “I still have many things to say to you, but you cannot bear them now. However, when He, the Spirit of truth, has come, He will guide you into all truth; for He will not speak on His own authority, but whatever He hears He will speak; and He will tell you things to come. He will glorify Me, for He will take of what is Mine and declare it to you." John 16:12-14
Many of those things to be revealed were revealed through Paul.
So you believe Jesus designated Paul as the Spirit of Truth?!
Amen! Exactly.