What religious idea did john calvin and martin luther disagree on

The answer is that a person's spiritual destiny is determined by God.  

Explanation:

John Calvin developed Calvinism during the 16th century, and Calvinism is the Protestant theological system, which develops Luther's doctrine of justification by faith alone and emphasizes the grace of God and the doctrine of predestination. Predestination is the doctrine that God has eternally chosen those whom he intends to save.

During the 16th century, Martin Luther developed Lutheranism, and the theology of Lutheranism is the justification of grace through faith alone for the sake of Jesus Christ, and concentrates on God's favour to every person and not on each person's action toward God. Lutherans believe that the understanding of God's favour depends upon proclamation and interpretation of the Bible.

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