2 Corinthians 2:7

So that contrariwise ye should rather forgive him and comfort him, lest by any means such a one should be swallowed up with his overmuch sorrow. Wherefore, I beseech you to confirm your love toward him.

Forgive ... comfort him ... The notion of some, going all the way back to Tertullian, that the man's sin was in any sense unforgivable is founded on a lack of perceiving the fact that the blood of Jesus Christ is more than sufficient to the cleansing of "all sin" (1 John 1:7), even of Christians. As a matter of truth, the incestuous person was hardly any greater sinner than many of the other Corinthians (1 Corinthians 6:8-11). The failure to believe Paul was here speaking of the incestuous person also stems from the failure to view a sin forgiven as being something infinitely removed from a sin unforgiven.

I beseech you to confirm your love toward him ... Nothing could be more unbecoming to a church, or to Christians, than to withhold forgiveness from a penitent Christian needing and asking it. It should be noted that Paul's request that forgiveness be extended is made in this letter and that there is no mention of a prior request to that effect.