For our boasting is this: the testimony of our conscience that we conducted ourselves in the world in simplicity and godly sincerity, not with fleshly wisdom but by the grace of God, and more abundantly toward you. 13 For we are not writing any other things to you than what you read or understand. Now I trust you will understand, even to the end 14 (as also you have understood us in part), that we are your boast as you also are ours, in the day of the Lord Jesus. —2 Corinthians 1:12-14.
Holiness with simple sincerity from God, according to His grace, is the basis of Paul’s dealing with the Corinthian church.