What was the name of the French theologian who established a theocracy in Geneva?

John Calvin was a key figure in the Protestant Reformation and is best known for establishing a theocratic government in Geneva, where he exerted significant influence over the city's religious and political life. He believed in the importance of a community governed by biblical principles and implemented a system where church leaders had authority over civil matters, creating a model of governance that fused religious and political power.

Calvin's reforms in Geneva included the establishment of a strict moral code, church discipline, and an emphasis on the sovereignty of God, which became foundational to Calvinist theology. His role as a theologian and church leader, along with his writings such as the "Institutes of the Christian Religion," positioned him as one of the most influential figures in shaping Protestant thought and practice during the Reformation, particularly within the Reformed tradition.

The other individuals listed had significant roles in their respective contexts, but they did not establish a theocracy in Geneva or have a similar influence on the reformation of governance intertwined with religion as Calvin did.