John Calvin (born : 10 July 150927 May 1564) was an influential French theologian and pastor during the Protestant Reformation. He was a principal figure in the development of the system of Christian theology later called Calvinism. Originally trained as a humanist lawyer, he broke from the Roman Catholic Church around 1530. After religious tensions provoked a violent uprising against Protestants in France, Calvin fled to Basel, Switzerland, where he published the first edition of his seminal work The Institutes of the Christian Religion in 1536.