What piece treaty formally accepted the division of Christianity in Germany?

The Peace of Augsburg, signed in 1555, formally accepted the division of Christianity in Germany. This treaty allowed for the coexistence of Catholicism and Lutheranism, granting rulers the authority to determine the official religion of their territories. It established the principle of "cuius regio, eius religio," meaning that the religion of the ruler would dictate the religion of the ruled. This was a significant step in the broader Protestant Reformation and the religious conflicts that followed.