French and imperial armies were manoeuvring across the road to Strasbourg in the summer of 1536, so a young refugee from Picardy made a detour to the south and stopped in Geneva for what was meant to be a single night. William Farel, a French preacher who was trying to reform the city's church, begged him to stay and help. John Calvin stayed, apart from three years of exile, until his death in 1564. He arrived with a reputation already made: in March of that year a printer in Basel had brought out his Institutes of the Christian Religion, a short Latin defence of the French Protestants whom Francis I, the king of France, was persecuting.
The defence came out of a lawyer's training. Calvin's father, the notary of the cathedral at Noyon, first meant his sons for the priesthood and then moved Calvin out of that path and into law; according to his early biographers Theodore Beza and Nicolas Colladon, he expected a lawyer to earn more than a priest. At Bourges Calvin studied under Andrea Alciati, an Italian humanist lawyer, and learned the Greek in which the New Testament was written. His first book, in 1532, was a commentary on De Clementia, Seneca's essay on mercy addressed to the emperor Nero. Somewhere in these years he broke with the Catholic Church. He left two accounts of it that do not agree, one sudden and one slow, and scholars place the change anywhere between 1529 and 1533. When the theologians of Paris denounced his friend Nicolas Cop, the university's rector, for an address calling for church reform, Calvin went into hiding. After placards attacking the Mass appeared in October 1534 he left France.
What was at stake for him was who had the right to say what God requires and who is saved. The Catholic answer was the church itself, through its priests, its sacraments and the pope. Calvin's answer fills the Institutes. People cannot know themselves without knowing God, and they know God truly only through Scripture, whose authority rests on the inner witness of the Holy Spirit and not on any institution's say-so. Salvation is God's free gift, received through faith, and God decided before anyone was born who would receive it. That doctrine, predestination, is the one his name carries now. For a believer hunted in France, it put the question of who is saved out of reach of the church that was hunting him.
The city resisted him from the start. At Easter 1538 Calvin and Farel refused to give communion in a quarrel with the city council over the bread to be used, a riot broke out in the church, and the council expelled them the next day. Calvin spent three years in Strasbourg as minister to a congregation of French refugees and married Idelette de Bure, a widow. Geneva recalled him in 1541, and the Ecclesiastical Ordinances passed that November set up pastors, teachers, elders and deacons for the city, and a Consistory of ministers and elders to oversee the conduct of its people. In 1553 Michael Servetus, a Spanish physician who denied the Trinity, came to Geneva after escaping Catholic imprisonment in France. Calvin denounced him and urged that he be beheaded; the council had him burned on 27 October. In 1559 Calvin opened an academy with Beza as rector, and within five years it taught some fifteen hundred students.
Calvin was buried in an unmarked grave, because the reformers did not want to be accused of starting a saint's cult around his body. The Reformed churches that grew from Geneva's model spread through Switzerland, France, the Netherlands and Scotland, and later across the Atlantic. In the Dutch church a dispute over predestination went to a national synod at Dordrecht in 1618–19, which ruled for Calvin's side. Max Weber, the German sociologist, took the later Calvinist habit of reading economic success as a sign of God's favour as the starting point of his account of capitalism, though that reading of success played only a small part in Calvin's own thinking. In 2000 the American philosopher Alvin Plantinga gave the name Aquinas/Calvin model to his account of how a believer can know God without arguing for it.