Augustine of Hippo
Catena Aurea · Markusevangelium 9
And if thy hand offend thee, cut it off: it is better for thee to enter into life maimed, than having two hands to go into hell, into the fire that never shall be quenched: Where their worm dieth not, and the fire is not quenched. And if thy foot offend thee, cut it off: it is better for thee to enter halt into life, than having two feet to be cast into hell, into the fire that never shall be quenched: Where their worm dieth not, and the fire is not quenched. And if thine eye offend thee, pluck it out: it is better for thee to enter into the kingdom of God with one eye, than having two eyes to be cast into hell fire: Where their worm dieth not, and the fire is not quenched. For every one shall be salted with fire, and every sacrifice shall be salted with salt. Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves, and have peace one with another.
(de Con. Evan. 4. 6) Here truly it appears that they who do acts of devotedness in the name of Christ, even before they have joined themselves to the company of Christians, and have been washed in the Christian Sacraments, are more useful than those who though already bearing the name of Christians, by their doctrine drag their followers with themselves into everlasting punishment; whom also under the name of members of the body, He orders, as an offending eye or hand, to be torn from the body, that is, from the fellowship itself of unity, that we may rather come to everlasting life without them, than with them go into hell. But the separation of those who separate themselves from them consists in the very circumstance of their not yielding to them, when they would persuade them to evil, that is, offend them. If indeed their wickedness becomes known to all the good men, with whom they are connected, they are altogether cut off from all fellowship, and even from partaking in the heavenly Sacraments. If however they are thus known only to the smaller number, whilst their wickedness is unknown to the generality,they are to he tolerated in such a way that we should not consent to join in their iniquity, and that the communion of the good should not be deserted on their account.