John Calvin

He was an influential French pastor during the Protestant Reformation.
He was a key figure in the development of the system of Christian theology which is now called Calvinism.
Originally trained as a lawyer, he broke from the Roman Catholic Church around 1530. After religious tensions started 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.
In that year, Calvin was recruited by William Farel to help reform the church in Geneva.
Calvin proceeded to Strasbourg, where he became the minister of a church of French refugees. He continued to support the reform movement in Geneva, and was eventually invited back to lead its church.
Following his return, Calvin introduced new forms of church goverment, despite the opposition of several powerful families in the city who tried to curb his authority. During this time, the trial of Michael Servetus was extended by libertines in an attempt to harass Calvin. However, since Servetus was also condemned, outside pressure from all over Europe forced the trial to continue. He was follewd by refuges and new additions to the city council, he forced his oppents out. Calvin spent his final years promoting the Reformation both in Geneva and throughout Europe.
He also exchanged cordial and supportive letters with many reformers, including Philipp Melanchthon and Heinrich Bullinger. In addition to the Institutes, he wrote commentaries on most books of the Bible, as well as theological treatises and confessional documents.
The Reformed and Presbyterian churches, which look to Calvin as a chief expositor of their beliefs, have spread throughout the world.
Calvin's writing and preachings provided the seeds for the branch of theology that bears his name.