In Institutes 3.3.19, John Calvin gives a “summary of the gospel” (cf. 3.3.1), in which he makes the important point that “the gospel,” the good news that Scripture and the church proclaim, includes not only the forgiveness or remission of sins (justification), but also renewal (sanctification), which derives from the general category of repentance. Both of these occur simultaneously, even though they are not the same.1
Calvin puts it this way:
Moreover if it is true, and nothing can be more certain, than that a complete summary of the Gospel is included under these two heads—viz. repentance and the remission of sins, do we not see that the Lord justifies his people freely, and at the same time renews them to true holiness by the sanctification of his Spirit? John, the messenger sent before the face of Christ to prepare his ways, proclaimed, “repent, for the kingdom of heaven is at hand,” (Mt. 11:10; 3:2). By inviting them to repentance, he urged them to acknowledge that they were sinners, and in all respects condemned before God, that thus they might be induced earnestly to seek the mortification of the flesh, and a new birth in the Spirit. By announcing the kingdom of God he called for faith, since by the kingdom of God which he declared to be at hand, he meant forgiveness of sins, salvation, life, and every other blessing which we obtain in Christ; wherefore we read in the other Evangelists, “John did baptize in the wilderness, and preach the baptism of repentance for the remission of sins,” (Mark 1:4; Luke 3:3). What does this mean, but that, weary and oppressed with the burden of sin, they should turn to the Lord, and entertain hopes of forgiveness and salvation? Thus, too, Christ began his preaching, “The kingdom of God is at hand: repent ye, and believe the Gospel,” (Mark 1:10). First, he declares that the treasures of the divine mercy were opened in him; next, he enjoins repentance; and, lastly, he encourages confidence in the promises of God. Accordingly, when intending to give a brief summary of the whole Gospel, he said that he behaved “to suffer, and to rise from the dead the third day, and that repentance and remission of sins should be preached in his name among all nations,” (Luke 24:26, 46). In like manner, after his resurrection the Apostles preached, “Him has God exalted with his right hand, to be a Prince and a Savior, for to give repentance to Israel and forgiveness of sins,” (Acts 5:31). Repentance is preached in the name of Christ, when men learn, through the doctrines of the Gospel, that all their thoughts, affections, and pursuits, are corrupt and vicious; and that, therefore, if they would enter the kingdom of God they must be born again. Forgiveness of sins is preached when men are taught that Christ “is made unto us wisdom, and righteousness, and sanctification, and redemption,” (1 Cor. 1:30), that on his account they are freely deemed righteous and innocent in the sight of God. Though both graces are obtained by faith (as has been shown elsewhere), yet as the goodness of God, by which sins are forgiven, is the proper object of faith, it was proper carefully to distinguish it from repentance.