1 Corinthians 5:2
And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you. And ye are puffed up, and have not rather mourned, that he that hath done this deed might be taken away from among you.
The deed is open fornication in the midst of the church, shameful and serious sexual sin committed by a member. The rebuke is for being puffed up over it and treating it lightly instead of mourning over it. The mourning called for is not feeling alone but acting so that he that did the deed might be taken away from among them and removed from fellowship.
Removal means exclusion from the fellowship and privileges of the church until the sin is dealt with, and merely confessing regret does not make continued fellowship appropriate. Tolerating the sin brings God's displeasure upon the church and can corrupt others, especially the young. The first letter exposed the wrongdoing so the church could repent and take action against those disgracing the church.
The report of the sin was brought by those who had the interest of the church at heart, and as God's appointed minister and faithful steward of the mysteries of God there was a duty not to fail in correcting it, judging the offender even while absent in body. The correction reproved impurity as contrary to the purity, devotion and piety God requires in the church, dealing firmly with the evil according to its aggravated character. Bringing dangers that threaten the prosperity of the church to God's messenger is right, and asking who told him hinders the work of warning and drawing back the erring from evil.