2 Corinthians 4:4
4:4 among whom the god of this age has blinded the minds of those who do not believe so they would not see the light of the glorious gospel of Christ, who is the image of God.
2 Corinthians 7:8
7:8 For even if I made you sad by my letter, I do not regret having written it (even though I did regret it, for I see that my letter made you sad, though only for a short time).
2 Corinthians 13:5
13:5 Put yourselves to the test to see if you are in the faith; examine yourselves! Or do you not recognize regarding yourselves that Jesus Christ is in you – unless, indeed, you fail the test!