John Calvin wrote in his Institutes (Book 4, Chapter 1, Paragraph 22):

To impart this blessing to us, the keys have been given to the Church (Mt. 16:19; 18:18). For when Christ gave the command to the apostles, and conferred the power of forgiving sins, he not merely intended that they should loose the sins of those who should be converted from impiety to the faith of Christ; but, moreover, that they should perpetually perform this office among believers…Therefore, in the communion of saints our sins are constantly forgiven by the ministry of the Church, when presbyters or bishops, to whom the office has been committed…

I just want to point out that the view which Calvin tries to squash there, that Christ “merely intended that they should loose the sins of those who should be converted from impiety to the faith of Christ” (as a once for all setup of the Christian system rather than a perpetual Nicolaitian muscle-flexing and lording it over God’s heritage) was held by Tertullian, himself a Catholic, who lived in the first decade of the 200s, at the very time that certain bishops in North Africa were inventing the doctrine of the keys which Calvin defends. (Yes, the Roman Catholic doctrine of the keys was actually invented in North Africa and then imported to Rome.)

Tertullian in chapter 21 of his treatise On Modesty, Claesson’s translation from, run by the illustrious Roger Pearse:

If it is because Our Lord has said to St. Peter, “Upon this rock I will build my church…and I will give unto thee the keys of the kingdom of heaven” or “and whatsoever thou shalt bind or loose on earth, shall be bound and loosed in heaven,” is it for this reason that you presume the power to bind and loose had transfered to you, i.e. to every church with some connection with St.Peter? But how is it possible that you are destroying, and altering the evident intention of Our Lord, who is giving this right alone to St.Peter and in person. “Upon thee” he says “I will build my church,” and “I will give unto thee the keys” not unto the church, “and whatsoever thou shalt bind or thou shalt loose,” not that which they shall bind nor they shall loose. For that we can learn even by the events. On him himself the church is erected, that is to say by him, he himself consecrated the keys of faith, because he said, “Ye men of Israel, hear these words, Jesus of Nasareth, a man approved of God among you” and what follows [i.e. his sermon in Acts 2]. He himself finally opened first of all the gate to the kingdom of Heaven in the baptism in Christ and by the baptism are loosened the sins, earlier bound and are bound those which never were loosened according to the true salvation…

He goes off on some strange tangents after this, but this much of what he says is perfectly on point.

That the power of binding and loosing was exercised once for all when Peter setup faith, repentance, and baptism as the entry requirements into the church, is deeply comforting and full of assurance.  Especially since biblically, baptism does not have to be “administered” by the bishop, presbyter, priest, Reformed elder, pastor, clergyman, guru, or whatever else Calvin and the Roman Catholic church might claim in that regard.  Baptism may be performed by any regular ole Christian, and Peter long ago turned usthe keys and loosed the sins of any who will believe in Christ, repent of their sins, and be baptized for the remissions of sins…thus giving us full assurance of salvation without having to kneel down and kiss the feet of any pope, bishop, presbyter, priest, or other philosopher-king, whether they be Catholic or Calvinist.

(The idea of this post occurred to me while watching Kevin DeYoung: Assurance Comes from Elders Proclaiming You Saved; 12 minutes because the particular place from Calvin’s Institutes was quoted, since Kevin DeYoung had said that assurance comes from having 10 elders tell you that they consider you to be in good standing with “the Church.”)