Human Letters Were Written in Hearts Before Written Letters

The Apostle Paul wrote this second letter to the Church at Corinth. Paul’s first visit to Corinth had previously occurred during his second missionary journey and lasted for almost two years (50-52 A.D.) ref: Paul's Visits and Letters to Corinth. In the letter Paul describes the Church there are the product of his preaching. 

2 Corinthians 3:1-3 Are we beginning to commend ourselves again? Or do we need, like some people, letters of recommendation to you or from you? You yourselves are our letter, written on our hearts, known and read by everyone. You show that you are a letter from Christ, the result of our ministry, written not with ink but with the Spirit of the living God, not on tablets of stone but on tablets of human hearts.

Paul is quite explicit here in declaring that the Church in Corinth was not a product of written Scriptures but a product of his preaching and that of others to the Corinthians. The notion of the church being formed from the writings of Paul is completely foreign to the New Testament and is a Reformation novelty. It is historically absurd. The Reformers used their novel teachings as a pretext to undermine the authority of the Historical Churches.