States within the Holy Roman Empire were the earliest territories to accept the Protestant Reformation, but by the later 1520s and 1530s religious change came to Denmark-Norway, Sweden, England, France, and eastern Europe. In most of these areas, a second generation of reformers built on Lutheran and Zwinglian ideas to develop their own theology and plans for institutional change. The most important of the second-generation reformers was John Calvin, whose ideas would profoundly influence the social thought and attitudes of European peoples and their descendants all over the world.