When the Lord inquires concerning the opinion of the multitudes, all the disciples answer; but when all the disciples are asked, Peter as the mouth and head of the Apostles answers for all, as it follows, 'Simon Peter answered and said, "You are Christ, the Son of the living God."'
For as with a zeal beyond the others he had confessed the King of heaven, he is deservedly entrusted more than the others with the keys of the heavenly kingdom, that it might be clear to all, that without that confession and faith none ought to enter the kingdom of heaven. By the keys of the kingdom He means discernment and power; power, by which he binds and looses; discernment, by which he separates the worthy from the unworthy. But this power of binding and loosing, though it seems given by the Lord to Peter alone, is indeed given also to the other Apostles, and is even now in the Bishops and Priests in every Church. But Peter received in a special manner the keys of the kingdom of heaven, and a supremacy of judicial power, that all the faithful throughout the world might understand that all who in any manner separate themselves from the unity of the faith, or from communion with him, such should neither be able to be loosed from the bonds of sin, nor to enter the gate of the heavenly kingdom.
How is it that some do presume to say that these things only apply to the living? Know they not that the sentence of anathema is nothing else but separation? They are to be avoided who are held of grievous faults, whether they are among the living, or not. For it is always necessary to fly from the wicked. Moreover there are diverse letters read of Augustine of religious memory, who was of great renown among the African bishops, which affirmed that heretics ought to be anathematized even after death. Such an ecclesiastical tradition other African Bishops also have preserved. And the Holy Roman Church also has anathematized some Bishops after death, although no accusation had been brought against their faith in their lifetimes.
Some Bishops and Priests, not understanding this passage, assume to themselves something of the lofty pretensions of the Pharisees, and suppose that they may either condemn the innocent, or absolve the guilty; whereas what will be inquired into before the Lord will be not the sentence of the Priests, but the life of him that is being judged. We read in Leviticus of the lepers, how they are commanded to show themselves to the Priests; and if they have the leprosy, then they are made unclean by the Priest; not that the Priest makes them leprous and unclean, but that the Priest has knowledge of what is leprosy and what is not leprosy, and can discern who is clean, and who is unclean. In the same way then as there the Priest makes the leper unclean, here the Bishop or Presbyter binds or looses not those who are without sin, or guilt, but in discharge of his function when he has heard the varieties of their sins, he knows who is to be bound, and who loosed.