How did the Peace of Augsburg of 1555 change the legal position of Lutheranism?

The Peace of Augsburg, promulgated in 1555, established the first permanent legal basis for the coexistence of Lutheranism and Roman Catholicism within the Holy Roman Empire.1

This agreement fundamentally changed the legal status of Lutheranism by granting state princes the authority to select either Lutheranism or Catholicism as the official religion of their respective territories. This principle, known as cuius regio, eius religio ("whose region, his religion"), made the chosen faith obligatory for subjects, though those who dissented were permitted to sell their property and emigrate.213

While the treaty officially ended religious conflict between the two recognized denominations, it excluded other Protestant groups, such as Calvinism. Additionally, the settlement included specific provisions for free imperial cities and certain ecclesiastical lands, though it remained a compromise that left some issues, such as the "ecclesiastical reservation," subject to ongoing tension. By providing this legal framework, the Peace of Augsburg allowed Germany to emerge from the 16th century as a religiously divided country, effectively ending the era of forced religious uniformity that Philip, Landgrave of Hesse, had long resisted through his leadership of the Schmalkaldic League.2145