We do not know what he said in his face to face meetings with his friends. We do know what he wrote. Although the Apostle John states in both his 2nd and 3rd letter that he would rather be with his recipients than write to them, I am glad he wrote nonetheless.
What John wrote gives us priceless understanding of definitive theology concerning the Person of Christ which we, humanly speaking, would not have had if it were not in writing. There were some in John’s day who did not believe that Jesus was authentically human. Angelic perhaps. Divine for sure. But a fully developed human being? No way!
John writes, “way!” In fact, to deny “way” is to be a deceiver (2 John 7). A deceiver is one who deliberately purports lies in the face of Truth. More than that, John escalates at the end of verse 7 that to deny the humanity of Christ is the essence of being antichrist.
To be antichrist is to break fellowship with the God of the universe Himself! John calls it wandering "beyond the teaching of Christ,"(v, 9.
This letter writing is serious business. The Apostle John appears to be a relational man. He was a loving leader. John loved God’s people with the very heart of God Himself. But had he followed his natural inclination to be with God’s people rather than write to them, we would have been doctrinally poorer for it.
Words spoken are good for the moment, but the written Word endures forever