3 Then because this saying also seemed to be that of one extolling himself greatly, this too he corrects, saying, “Yet am I not hereby justified.” What then? Ought we not to judge ourselves and our own misdeeds? Yes surely: there is great need to do this when we sin. But Paul said not this, “For I know nothing,” says he, “against myself.” What misdeed then was he to judge, when he “knew nothing against himself?” Yet, says he, “he was not justified.” We then who have our conscience filled with ten thousand wounds, and are conscious to ourselves of nothing good, but quite the contrary; what can we say?
And how could it be, if he knew nothing against himself that he was not justified? Because it was possible for him to have committed certain sins, not however, knowing that they were sins. From this make your estimate how great shall be the strictness of the future judgment. It is not, you see, as considering himself unblameable that he says it is so unmeet for him to be judged by them, but to stop the mouths of those who were doing so unreasonably. At least in another place, even though men's sins be notorious, he permits not judgment unto others, because the occasion required it. “For why do you judge your brother,” says he, or, “thou, why do you set at nought your brother?” For thou were not enjoined, O man, to judge others, but to test your own doings. Why then do you seize upon the office of the Lord? Judgment is His, not yours.
To which effect, he adds, “Therefore judge nothing before the time, until the Lord come; who will both bring to light the hidden things of darkness, and make manifest the counsels of the hearts, and then shall each man have his praise from God.” What then? Is it not right that our teachers should do this? It is right in the case of open and confessed sins, and that with fitting opportunity, and even then with pain and inward vexation: not as these were acting at that time, of vain-glory and arrogance. For neither in this instance is he speaking of those sins which all own to be such, but about preferring one before another, and making comparisons of modes of life. For these things He alone knows how to judge with accuracy, who is to judge our secret doings, which of these be worthy of greater and which of less punishment and honor. But we do all this according to what meets our eye. “For if in my own errors,” says he, “I know nothing clearly, how can I be worthy to pass sentence on other men? And how shall I who know not my own case with accuracy, be able to judge the state of others?” Now if Paul felt this, much more we. For (to proceed) he spoke these things, not to exhibit himself as faultless, but to show that even should there be among them some such person, free from transgression, not even he would be worthy to judge the lives of others: and that if he, though conscious to himself of nothing declare himself guilty, much more they who have ten thousand sins to be conscious of in themselves.
Source: Homilies on First Corinthians (New Advent)