The Peace of Augsburg, also called the Augsburg Settlement, was a treaty between Charles V, Holy Roman Emperor (the predecessor of Ferdinand I) and the Schmalkaldic League, signed on September 1555 at the imperial city of Augsburg. It officially ended the religious struggle between the two groups and made the legal division of Christendom permanent within the Holy Roman Empire, allowing rulers to choose either Lutheranism or Roman Catholicism as the official confession of their state. Calvinism was not allowed until the Peace of Westphalia.
what agreement gave religious freedom to the lutherans
Augsburg Settlement