1 Corinthians 7:16

7:16 For how do you know, wife, whether you will bring your husband to salvation? Or how do you know, husband, whether you will bring your wife to salvation?

1 Corinthians 9:20-22

9:20 To the Jews I became like a Jew to gain the Jews. To those under the law I became like one under the law (though I myself am not under the law) to gain those under the law. 9:21 To those free from the law I became like one free from the law (though I am not free from God’s law but under the law of Christ) to gain those free from the law. 9:22 To the weak I became weak in order to gain the weak. I have become all things to all people, so that by all means I may save some.

1 Corinthians 9:2

9:2 If I am not an apostle to others, at least I am to you, for you are the confirming sign of my apostleship in the Lord.

1 Corinthians 2:10

2:10 God has revealed these to us by the Spirit. For the Spirit searches all things, even the deep things of God.