As always, the blog titles and Scripture references are all original to Calvin.
Institutes of the Christian Religion (1559) - John Calvin
Book 3 - How We Receive the Grace of Christ
Chapter 4 - Impurity of Sophists' doctrine of repentance;
discussion of confession and satisfaction
Sections 16-25 - Criticism of Roman injurious practices
Section 21 - The uncertainty of priestly binding and loosing
It is uncertain because sinful priests absolve or require penance, not according to the Word, which they could do - 1 Cor 6:9-10.
Section 22 - The difference between perverted and right use of the power of the keys
Forgiveness doesn't depend on the priest figuring out whose repentance is real.
Only the sinner's trust in God's mercy is required.
When the minister "as a herald, publishes what has been dictated to him from the Word of God [he] cannot err."
Section 23 - Perverse claims exposed
Matt 18:18 doesn't apply to confessing to a priest;
it deals with public offense against another, not with private confession.
"The priest does not so much forgive sins as pronounce and declare them forgiven."
They say part of God's forgiveness involves fulfilling church-required "penalty and satisfaction." This adds to God's free promise of forgiveness, taking away assurance and eroding the Gospel.
Section 24 - Summary
Freeing the conscience where the Word doesn't, or requiring works where the Word offers free grace, both drive the godly either into despair or apathy.
Section 25 - General presentation and refutation of the Roman doctrine
Rome says God's punishment remains after He forgives.
[We call this "consequences"].
Satisfaction doesn't fit with FREE forgiveness - Isa 43:25; 52:3; Rom 3:24-25; 5:8; Col 2:13-14; 2 Tim 1:9; Titus 3:5; Acts 10:43; 2 Cor 5:19-21.