What does 2 Corinthians 1:20 mean?
Paul is answering the charge from some in Corinth that he selfishly changed his travel plans to visit them, saying both "yes" and "no" to his commitments at the same time. Paul's defense is as serious as the accusation is frivolous.First, he has insisted he was not saying "yes" and "no" at the same time, but that in Christ, the answer is always "yes." Now he adds that all the promises of God find their "yes" in Christ. In other words, all of God's Old Testament promises are fulfilled in Jesus. Christ is the "yes" to every one of them.
Paul, who represents Christ and does His work, seems to be saying that even his change of travel plans reflects the "yes" found in Jesus. Motivated to be as Christ to the Corinthians, Paul altered course to serve them better. He acknowledged God's leading and responded by saying "amen" to God for His glory. Just as the Corinthians themselves affirmed Christ as God's "yes," Paul agreed with and affirmed God's will for him in Christ by holding off on his return visit to Corinth.