The Reformation, or, more fully, the Protestant Reformation, was a schism in Western Christianity initiated by Martin Luther and continued by John Calvin, Huldrych Zwingli, and other Protestant Reformers in 16th-century Europe. It is usually considered to have started with the publication of the Ninety-five Theses by Martin Luther in 1517 and lasted until the end of the Thirty Years' War in 1648.
Although there had been earlier attempts to reform the Catholic Church – such as those of Jan Hus, Peter Waldo, John Wycliffe, and Girolamo Savonarola – Luther is widely acknowledged to have started the Reformation with the Ninety-five Theses. Luther began by criticising the sale of indulgences, insisting that the Pope had no authority over purgatory and that the Catholic doctrine of the merits of the saints had no foundation in the Bible. The Protestant Reformation incorporated doctrinal changes such as a complete reliance on Scripture as the only source of proper belief (sola scriptura) and the belief that faith in Jesus, and not good works, is the only way to obtain God's pardon for sin (sola fide). The core motivation behind these changes was theological, though many other factors played a part, including the rise of nationalism, the Western Schism that eroded loyalty to the Papacy, the perceived corruption of the Roman Curia, the impact of humanism, and the new learning of the Renaissance that questioned much traditional thought.
The initial movement within Germany diversified, and other reformers arose independently of Luther. The spread of Gutenberg's printing press provided the means for the rapid dissemination of religious materials in the vernacular. The largest groups were the Lutherans and Calvinists. Lutheran churches were founded in Germany, the Baltic and Scandinavia, and Reformed ones in Switzerland, Hungary, France, the Netherlands and Scotland.
