He began his theological career in France, but was forced to flee to Basle in Switzerland after embracing Protestantism in the early 1530s. He attempted a re-ordering of society on reformed Christian principles, with strong and sometimes ruthless control over the private lives of citizens. From 1541 he lived in Geneva, where he established the first Presbyterian government. He exerted an important influence on the development of Protestant thought; his theological system, Calvinism, was further developed by his followers, notably Theodore Beza (1519–1605).