2 Corinthians 13:1-4

This will be my third visit to you. "Every matter must be established by the testimony of two or three witnesses." I already gave you a warning when I was with you the second time. I now repeat it while absent: On my return I will not spare those who sinned earlier or any of the others,

(v1-2, NIV)

Verse 1 is referenced from the Old Testament.

One witness is not enough to convict a man accused of any crime or offense he may have committed. A matter must be established by the testimony of two or three witnesses.

(Deuteronomy 19:15)

When Paul comes to them, he will be able to confirm them and their sins. He desperately wants to see them following Jesus and turning away from their sins, but some of them have been deceived by false apostles.

since you are demanding proof that Christ is speaking through me. He is not weak in dealing with you, but is powerful among you. For to be sure, he was crucified in weakness, yet he lives by God's power. Likewise, we are weak in him, yet by God's power we will live with him to serve you.

(v3-4, NIV)

They don't believe Paul or his assertion that Christ is speaking through him. To some people, Jesus being crucified on the cross is a sign of weakness. Through that act alone, they may brush Jesus off as a weakling who they could never follow. Nothing could be further from the truth. He lives by God's power. We know that God's power is strong.

For the foolishness of God is wiser than men, and the weakness of God is stronger than men.

(1 Corinthians 1:25, ESV)

Though we may sometimes seem weak as followers of Jesus, we know that we are strong in Him. We will live with him because of the power of God. Don't be deceived by these worldly thoughts. Jesus was raised, and he was raised in power.