2 Corinthians 1:12-14 meaning

Having finished his introductory comments, Paul begins the main body of his second letter to the Corinthians by defending his character and integrity. He begins with For our proud confidence (or boasting) is this (v 12). The rest of Chapter 1 and the beginning of Chapter 2 is one side of a two-sided conversation. 

As Paul begins verse 12, he is giving testimony as to the basis of his own integrity, which had been challenged, For our proud confidence is this: the testimony of our conscience (v 12). For Paul, this was a powerful statement as a clear conscience was foundational to his ministry. The following verses show that examining his conscience and operating out of a clear conscience was a theme for Paul.

In Paul's letters to Timothy, he urges: 

"But the goal of our instruction is love from a pure heart and a good conscience and a sincere faith."
(1 Timothy 1:5) 

In 1 Timothy 3:9, he says that church leaders should lead by "holding to the mystery of the faith with a clear conscience." 

Giving focus to his own ministry, he writes in 2 Timothy 1:3, "I thank God, whom I serve with a clear conscience, the way my forefathers did." 

When Paul faced accusations from the chief priests and the Sanhedrin, he faced them courageously: 

"Paul, looking intently at the Council, said, 'Brethren, I have lived my life with a perfectly good conscience before God up to this day.'"
(Acts 23:1) 

In affirming his love for the Jewish people, his people, he declared to the Roman church in Romans 9:1, "I am telling the truth in Christ, I am not lying, my conscience testifies with me in the Holy Spirit." 

In his letter to the Romans, Paul elevates this point to a general principle, saying "…whatever is not from faith is sin" (Romans 14:23b). Paul teaches that we should follow our conscience, and if we violate our conscience, then that is a sin. 

In Paul's case, he has examined himself, and is confident his motives are pure (2 Corinthians 13:5). He says something similar in his first letter to Corinth, but maintains humility about it, recognizing that at the end of the day everyone will be judged truly by Jesus:

"For I am conscious of nothing against myself, yet I am not by this acquitted; but the one who examines me is the Lord. Therefore do not go on passing judgment before the time, but wait until the Lord comes who will both bring to light the things hidden in the darkness and disclose the motives of men's hearts; and then each man's praise will come to him from God."
(1 Corinthians 4:4-5)

So Paul is stating that he has laid bare his inner conscience before God, and is convinced he is following God wholeheartedly. But he recognizes that God will ultimately decide men's hearts. He now begins to recognize this, that true wisdom comes from the grace of God.

The basis for this testimony of our conscience is that he has conducted himself towards the Corinthians in holiness and godly sincerity. His proud confidence does not come from himself or fleshly wisdom, but from the grace of God. 

It is likely this self-examination of his own conscience which Paul is referring to in Chapter 13 when he commands the Corinthians to "Test yourselves to see if you are in the faith; examine yourselves!" To be "in the faith" would be to walk consistent with what they know to be true and right. Paul has examined himself, and stands before the Corinthians saying "I know of nothing in which I am not living faithfully." In saying this, Paul is essentially appealing to God as a witness, who knows all the thoughts and intents of the heart (Hebrews 4:12). 

Paul contrasts confidence that comes from the grace of God with confidence that stems from fleshly wisdom. Fleshly wisdom refers to the ways, values, and means of this world. The Greek word, "sarkinos," translated here as fleshly can also be translated "carnal." Paul uses this term in his writings as an opposite for godly spirituality. That is evident here, as Paul contrasts fleshly wisdom to the grace of God and holiness and godly sincerity. Paul is confident that his intent was focused on following God, and doing what was best for the Corinthian believers; he is not following the world's self-seeking and exploitative ways. 

Paul is then declaring that his proud confidence that he is in the right comes not from anything of this world, but from Christ. Paul uses the Greek word "kauchesis" translated proud confidence six times in 2 Corinthians, and applies it several times to boasting to others about the faithfulness of the Corinthian believers. An example is in Chapter 8, where Paul asks them to give a generous offering to help the persecuted Jews still residing in Judea. Here the phrase "reason for boasting" is the translation of "kauchesis":

"Therefore openly before the churches, show them the proof of your love and of our reason for boasting about you."
(2 Corinthians 8:24)

Paul has proud confidence that he and Timothy have conducted themselves in a godly manner while in the world, but especially toward you—the recipients of this letter. For we write nothing else to you than what you read and understand, and I hope you will understand until the end (v 13). 

Paul desires the Corinthians to read and understand. But he adds that he wants them to understand until the end. We can infer from verse 14 that the end in mind is the day of our Lord Jesus (v 14). The day of our Lord Jesus refers to the day when Jesus will return and judge the earth. All believers will have their works evaluated, and be given rewards according to their deeds (2 Corinthians 5:10). It seems Paul's hope is that the Corinthians will constantly keep in mind Paul's admonition to live each day for "that day"—to live each day with the ultimate goal in mind to live a life that pleases God. 

Apparently Paul thought the Corinthians understood to some extent, saying just as you also partially did understand us, that we are your reason to be proud as you also are ours, in the day of our Lord Jesus (v 14).

The picture Paul paints here for Paul and Timothy to be proud of the Corinthians and the Corinthians to be proud of Paul and Timothy refers to the day of our Lord. This infers that when those who ministered to us are rewarded by Christ for deeds done in their life, those to whom they ministered will be proud of them. It will be like seeing a loved one receive a great reward. Paul desires that all involved keep in mind that our primary purpose in life is to live as a faithful witness and please God with our lives. 

Again, we do not have the other side of the story. It seems, however, from verse 14 and other references that there was another letter Paul had written to the Corinthians, apart from this letter and 1 Corinthians, that is now lost to us. In 1 Corinthians 5:9, Paul says "I wrote you in my letter" and again in verse 11, "But actually, I wrote to you." 

Then in 2 Corinthians 2:3-4, he refers again to a letter that seems to be a letter other than 1 Corinthians, 

"This is the very thing I wrote you, so that when I came, I would not have sorrow from those who ought to make me rejoice; For out of much affliction and anguish of heart I wrote to you with many tears; not so that you would be made sorrowful, but that you might know the love which I have especially for you."
(2 Corinthians 2:3-4)

Perhaps some in the Corinthian church did not understand all that Paul and Timothy wrote in that letter, and this lack of understanding played a part in the accusations against him. So, he is declaring to them, on the basis of his clear conscience what he was writing to them was intended to be plain and clear, that he says what he means and means what he says. 

Just as you also partially did understand us might be a reference to contents within the "unknown" letter, but also could be a reference to 1 Corinthians 2:4-5, "and my message and preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and of power." Perhaps the lack of clarity in the unknown letter is part of the reason it was lost to us. 

In any case, Paul is emphasizing to the Corinthians that he wants them to clearly understand his words and his heart.

That we are your reason to be proud as you also are ours, in the day of the Lord Jesus (v 14). Paul is now revealing that the proud confidence is the expected result each party should have for the other. Paul expects that in the day of the Lord Jesus he and Timothy will be proud of the Corinthians as they are rewarded by Christ for their ministry to Paul and Timothy. Similarly, Paul and Timothy expect the Corinthians will be proud of them as they are rewarded for their ministry to the Corinthians. By continuing to keep their eyes on the prize of the upward call in Christ to please Him in all things, they can all receive a great reward from Jesus for their faithfulness. 

As Paul and Timothy recall the prayers of the Corinthians for them in verse 11, they develop a theme of their mutual mission and partnership. Each benefits the other by ministering to them. Each will benefit from being proud of the reward each receives from Jesus for their ministry to the other. And it is implied that each will benefit from being rewarded for their faithful service to Jesus by serving one another.