2 Corinthians 13:1-7
2 Cor 13:1 (KJB)
This is the third time I am coming to you. In the mouth of two or three witnesses shall every word be established.
Here Paul is telling the Corinthians that he will be coming to visit them. This visit may have been for the purpose of shutting the mouths of the false teachers. (Deu 19:15 KJV) One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established. Paul also takes the procedure from Deuteronomy concerning the validation of accusations. One person is not sufficient to establish an accusation because one person can be out for revenge and that is why Paul is going to require multiple witnesses to validate any accusations the false teachers have leveled against him.
2 Cor 13:2 (KJB)
I told you before, and foretell you, as if I were present, the second time; and being absent now I write to them which heretofore have sinned, and to all other, that, if I come again, I will not spare:
Here Paul is basically saying that when he finally does come to Corinth he is not going to spare any method to put to death the accusations which were made against him. Paul even had the right to use legal means. Paul desired to rid the church of all the evil which had invaded and then pervaded that church, although there may have been some who did not believe the accusations against Paul, but it always seems those who wreak havoc in churches always seem to get the preeminence instead of getting the boot. Paul is warning those who have sinned but he wants everyone to know that if they follow in the footsteps of the false teachers and those who have sinned, then they will not be exempt from the punishment that the others will receive. This should also be a warning to all Christians that those who want to follow the wrong crowd in a church will face consequences.
2 Cor 13:3 (KJB)
Since ye seek a proof of Christ speaking in me, which to you-ward is not weak, but is mighty in you.
There were a group of people at Corinth who demanded that Paul prove that he was a true Apostle and that Christ was really speaking through him. He would give them ample proof upon his arrival in Corinth. This time though, he would be coming in the spirit of being a disciplinarian. Just as the Lord Jesus Christ came the first time to deal with sin and be an advocate for His people, but the second time He will return as the judge of all unsaved mankind. Paul will also come to Corinth in this manner and will show that he has God-given authority to deal with those who have brought turmoil into the church. Paul had to start dealing with the situation there as soon as possible or else the church could suffer a dissolution because of all the dissension which the false teachers have caused. This should be a warning to all churches that once false teachers are given a platform, the end of the church, that is a church which still preaches truth, will gradually come to pass.
2 Cor 13:4 (KJB)
For though he was crucified through weakness, yet he liveth by the power of God. For we also are weak in him, but we shall live with him by the power of God toward you.
When the Lord Jesus Christ was crucified, He was possessing a human body with all its frailties. Those who looked upon Christ at the crucifixion saw a man who was tortured and dying so they had mocked him believing they were mocking a weak man. (Mat 27:42 KJV) He saved others; himself he cannot save. If he be the King of Israel, let him now come down from the cross, and we will believe him.  The reality is that they had no idea what was transpiring. If Christ would have come down from the cross and saved Himself, then there could have been no salvation in the world. Jesus was vindicated by being raised from the dead by God who showed the world that Jesus was His Son. Just as in the case of how the world saw Christ, the world sees Christians the same way as being weak but one day when the Lord returns, he will endue them with His power for all eternity. For now, Paul is stating that even though he is weak in the flesh, when he comes to Corinth, they will experience the power of God concerning their situation.
2 Cor 13:5 (KJB)
Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
Examine - Try or put to the test
Prove - Scrutinize or test
Reprobates - Rejected, depraved, or disqualified
Here is a warning not only to the Corinthian Christians but to all those who claim to be Christians. Paul is telling them to examine themselves, that is, put their motives and actions to the test to see if they are truly saved. Paul then states again but more strongly that they are to prove themselves. The Greek word for “prove” carries with it the meaning of “eliminate the dross and recover the valuable or genuine remains.” Paul wants them to examine themselves very closely, not leaving out any areas of their life. He wants them to know completely and be fully assured that they are Christians and not just church goers. He does this because he does not want those who think they are saved but are truly reprobates to continue on in their present state. The day of salvation is always today and as long as a person lives, there is always a chance that a person can be saved. The final separation will be on Judgment Day when Christ separates the sheep, His saved, from the goats, the unsaved. This is why Paul wants them to test themselves as David as God to test him. (Psa 139:23 KJV) Search me, O God, and know my heart: try me, and know my thoughts: David wanted God to search his heart, to try him and to know his thoughts. How many of us would be willing to undergo that kind of examination but that is exactly the type of analysis which Paul had in mind.
2 Cor 13:6 (KJB)
But I trust that ye shall know that we are not reprobates.
The Corinthian church had spent much time examining Paul and he was confident that they would not consider him to be a reprobate. Paul was always making sure of his testimony that it completely brought glory to God and did not puff himself up in any manner taking away from Christ. Paul never desired to place himself first, to come between Christ and other people. This is what the false teachers did. They puffed themselves up and the people did not see Christ but only saw them.
2 Cor 13:7 (KJB)
Now I pray to God that ye do no evil; not that we should appear approved, but that ye should do that which is honest, though we be as reprobates.
Approved - Acceptable or esteemed
Paul had prayed to God that the Corinthian Christians would live lives becoming that of Christians. He would have loved it that the church would be free from sin. Paul also knew that the church at Corinth would not be trouble free and he was not asking it to be so, just so he could appear to others to be totally approved as if he founded a perfect church without any problems. He wanted them to be honest in all their dealings in life because he was willing to appear to others as a reprobate if it would have helped in their salvation. What he prayed for was these Christians would continue to live in the power of the Lord and as redeemed before the rest of the world. He wanted them to be in good standing, not only before others but before God.