If ever there were a verse of Scripture totally ignored by modern Christianity, it’s this one (from 1 Cor 5:5)
παραδουναι τον τοιουτον τω σατανα εις ολεθρον της σαρκος ινα το πνευμα σωθη εν τη ημερα του κυριου.
Why does Paul say such a thing? According to Calvin, he says such a thing in order to urge the Church to make use of its power of excommunication-
… delivering over to Satan is an appropriate expression for denoting excommunication; for as Christ reigns in the Church, so Satan reigns out of the Church … As, then, we are received into the communion of the Church, and remain in it on this condition, that we are under the protection and guardianship of Christ, I say, that he who is cast out of the Church is in a manner delivered over to the power of Satan, for he becomes an alien, and is cast out of Christ’s kingdom.
Naturally outside of Christ’s kingdom there’s no protection and Satan is free to do as he wishes; in the same way that a man thrown into a cage with a pit bull is subject to the ravaging of that particular beast, lacking, as he does, the protection offered by the fencing.
Paul’s meaning is not that the person who is chastised is given over to Satan to be utterly ruined, or so as to be given up to the devil in perpetual bondage, but that it is a temporary condemnation, and not only so, but of such a nature as will be salutary. For as the salvation equally with the condemnation of the spirit is eternal, he takes the condemnation of the flesh as meaning temporal condemnation.
When the person excommunicated gets the tar beat out of them because Christ no longer protects them via the community of faith, they (hopefully) come to their senses and return, in repentance, to their former fidelity. That, at any rate, is the purpose of excommunication: i.e., to drive the excommunicated soul to repentance.
Perhaps if the Church practiced this aspect of discipline more widely, fewer people would go down the path of self destruction and immorality might even be curbed.
But don’t worry, I’m not holding my breath. The modern Church is far too weak and will-less to apply such discipline. It’s too afraid that it will ‘lose members’ – as though persons living in immorality were really members anyway.