The apostle in these verses attests their integrity by the sincerity of their conversation. This he does not in a way of boasting and vain-glory, but as one good reason for desiring the help of prayer, as well as for the more comfortably trusting in God (Heb. 13:18), and for the necessary vindication of himself from the aspersions of some persons at Corinth, who reproached his person and questioned his apostleship. Here,
I. He appeals to the testimony of conscience with rejoicing (2 Cor. 1:12), in which observe, 1. The witness appealed to, namely, conscience, which is instead of a thousand witnesses. This God’s deputy in the soul, and the voice of conscience is the voice of God. They rejoiced in the testimony of conscience, when their enemies reproached them, and were enraged against them. Note, The testimony of conscience for us, if that be right and upon good grounds, will be matter of rejoicing at all times and in all conditions. 2. The testimony this witness gave. And here take notice, Conscience witnessed, (1.) Concerning their conversation, their constant course and tenour of life: by that we may judge of ourselves, and not by this or that single act. (2.) Concerning the nature or manner of their conversation; that it was in simplicity and godly sincerity. This blessed apostle was a true Israelite, a man of plain dealing; you might know where to have him. He was not a man who seemed to be one thing and was another, but a man of sincerity. (3.) Concerning the principle they acted from in all their conversation, both in the world and towards these Corinthians; and that was not fleshly wisdom, nor carnal politics and worldly views, but it was the grace of God, a vital gracious principle in their hearts, that cometh from God, and tendeth to God. Then will our conversation be well ordered when we live and act under the influence and command of such a gracious principle in the heart.
II. He appeals to the knowledge of the Corinthians with hope and confidence, 2 Cor. 1:13, 14. Their conversation did in part fall under the observation of the Corinthians; and these knew how they behaved themselves, how holily, and justly, and unblamably; they never found any thing in them unbecoming an honest man. This they had acknowledged in part already, and he doubted not but they would still do so to the end, that is, that they would never have any good reason to think or say otherwise of him, but that he was an honest man. And so there would be mutual rejoicing in one another. We are your rejoicing, even as you also are ours in the day of the Lord Jesus. Note, It is happy when ministers and people do rejoice in each other here; and this joy will be complete in that day when the great Shepherd of the sheep shall appear.