In 2 Corinthians, Paul defends his ministry as false prophets had come into the church with cynicism. Paul reminds the Corinthians to stand firm in Christ, keeping soft hearts and a clear conscience, being informed with the Word, and relying on our deposit of the Holy Spirit.
And it is God who establishes us with you in Christ, and has anointed us, and who has also put his seal on us and given us his Spirit in our hearts as a guarantee.
2 Corinthians 1:21-22