linguistic:translation, structural:reformatting, linguistic:paraphrasing
Calvin and Reformed theology

Calvin and Luther believed free will does not co-operate with God's grace which, according to them, cannot be rejected (see monergism). The Lutheran Augsburg Confession says of baptism, "Lutherans teach that it is necessary to salvation and that by baptism the grace of God is offered and that children are to be baptized, who by baptism, being offered to God, are received into God's favor." The French reformer John Calvin expanded and further developed these Augustinian themes in his systematic Institutes of the Christian Religion in 1536.

The logical structure of Calvinism is often expressed as the acronym, TULIP. These five categories do not comprise Calvinism in its entirety; they simply encapsulate its central, definitive doctrines.

The notion that God has foreordained who will be saved is generally called predestination. The concept of predestination peculiar to Calvinism, " double-predestination ", (in conjunction with limited atonement) is the most controversial expression of the doctrine. According to Reformed theology, the "good news" of the gospel of Christ is that God has freely granted the gift of salvation to those the Holy Spirit causes to believe; what he freely grants to some (the "elect" individuals), he withholds from others (the "reprobate" individuals).

Calvin sought to provide assurance to the faithful that God would actually save them. His teaching implied what came to be known as the doctrine of the perseverance of the saints, the notion that God would actually save those who were his Elect. The actual status and ultimate state of any man's soul were unknown except to God. When assurance of election was rigorously pressed as an experience to be sought, especially by the Puritans, this led to a legalism as rigid as the one Protestantism sought to reject, as men were eager to demonstrate that they were among the chosen by the conspicuous works-righteousness of their lives.

The relatively radical positions of Reformed theology provoked a strong reaction from both Roman Catholics and Lutherans.