The Western Schism, or Papal Schism, was a prolonged period of crisis in Latin Christendom from 1378 to 1416, when there were two or more claimants to the See of Rome and thus it was difficult to discern who the true Pope was. The conflict was political, rather than doctrinal, in nature.
The Renaissance was a period of great cultural change and achievement, marked in Italy by a classical orientation and an increase of wealth through mercantile trade. The City of Rome, the Papacy, and the Papal States were all affected by the Renaissance. On the one hand, it was a time of great artistic patronage and architectural magnificence, where the Church patroned such artists as Michelangelo, Brunelleschi, Bramante, Raphael, Fra Angelico, Donatello, and da Vinci. On the other hand, wealthy Italian families often secured episcopal offices, including the papacy, for their own members, some of whom were known for immorality, such as Alexander VI and Sixtus IV.
In the early 16th century, movements were begun by two theologians, Martin Luther and Ulrich Zwingli, that aimed to reform the Church. Unlike earlier reformers they considered the root of corruptions to be doctrinal (rather than simply a matter of moral weakness or lack of ecclesiastical discipline) and thus they aimed to change contemporary doctrines to fit their idea of the "true gospel". The Protestant Reformation is so called because the movement's leaders "protested" against the ecclesiastical hierarchy and the pope, essentially electing to institute their reforms separately from it. The term "Protestant", however, was not originally used by these leaders; instead, they called themselves "evangelical", emphasizing the "return to the true gospel (Greek: "euangelion")".
The beginning of the Protestant Reformation is generally identified with Martin Luther and the posting of the 95 Theses in 1517 in Wittenburg, Germany. Early protest was against corruptions such as simony, episcopal vacancies, and the sale of indulgences. The Protestant position, however, would come to incorporate doctrinal changes such as sola scriptura and sola fide. The three most important traditions to emerge directly from the Protestant Reformation were the Lutheran, Reformed (Calvinist, Presbyterian, etc.), and Anglican traditions, though the latter group identifies as both "Reformed" and "Catholic", and some subgroups reject the classification as "Protestant".
The Protestant Reformation may be divided into two distinct but basically simultaneous movements, the Magisterial Reformation and the Radical Reformation. The Magisterial Reformation involved the alliance of certain theological teachers (Latin: "magistri") such as Luther, Huldrych Zwingli, John Calvin, Cranmer, etc. with secular magistrates who cooperated in the reformation of Christendom. Radical Reformers, besides forming communities outside state sanction, often employed more extreme doctrinal change, such as the rejection of tenants of the Councils of Nicaea and Chalcedon. Often the division between magisterial and radical reformers was as or more violent than the general Catholic and Protestant hostilities.
The Protestant Reformation spread almost entirely within the confines of Northern Europe, but did not take hold in certain northern areas such as Ireland and parts of Germany. By far the magisterial reformers were more successful and their changes more widespread than the radical reformers. The Catholic response to the Protestant Reformation is known as the Counter Reformation, or Catholic Reformation, which resulted in a reassertion of traditional doctrines and the emergence of new religious orders aimed at both moral reform and new missionary activity. The Counter Reformation reconverted approximately 33% of Northern Europe to Catholicism and initiated missions in South and Central America, Africa, Asia, and even China and Japan. Protestant expansion outside of Europe occurred on a smaller scale through colonization of North America and areas of Africa.
Martin Luther was an Augustinian friar and professor at the University of Wittenberg. In 1517, he published a list of 95 Theses, or points to be debated, concerning the illicitness of selling indulgences. Luther had a particular disdain for Aristotelian philosophy, and as he began developing his own theology, he increasingly came into conflict with other scholars. Soon, Luther began to develop his theology of justification, or process by which one is "made right" (righteous) in the eyes of God.
In Catholic theology, one is made righteous by a progressive infusion of grace accepted through faith and cooperated with through good works. Luther's doctrine of justification was different. He said justification meant "the declaring of one to be righteous", where God imputes the merits of Christ upon one who remains without inherent merit. In this process, good works are more of an unessential byproduct that contribute nothing to one's own state of righteousness. Conflict between Luther and leading theologians lead to his gradual rejection of authority of the Church hierarchy. In 1520, he was condemned for heresy by the papal bull "Exsurge Domine", which he burned at Wittenburg along with books of canon law.
John Calvin was a French cleric and doctor of law turned Protestant reformer in the second generation of the Reformation. He was well known for publishing the "Institutes of the Christian Religion", in 1536 (later revised), and became a leader of the Reformed church in Geneva, which became an "unofficial capital" of Reformed Christianity in the second half of the sixteenth century. He had great authority in the city and over the city council, such that he has (rather ignominiously) been called a "Protestant pope".
Calvin established an eldership together with a "consistory", where pastors and the elders established matters of religious discipline for the Genevan population. Calvin's theology is best known for his doctrine of (double) predestination, which held that God had, from all eternity, providentially foreordained who would be saved (the elect) and likewise who would be damned (the reprobate). Predestination was not the dominant idea in Calvin's works, but it would seemingly become so for many of his Reformed successors.
Unlike other reform movements, the English Reformation began by royal influence. Henry VIII considered himself a thoroughly Catholic King, and in 1521 he defended the papacy against Luther in a book he commissioned entitled, "The Defense of the Seven Sacraments", for which Pope Leo X awarded him the title "Fidei Defensor" (Defender of the Faith). However, the king came into conflict with the papacy when he wished to annul his marriage with Catherine of Aragon, for which he needed papal sanction. Catherine, among many other noble relations, was the aunt of Emperor Charles V, the papacy's most significant secular supporter. The ensuing dispute eventually lead to a break from Rome and the declaration of the King of England as head of the English (Anglican) Church. England then experienced a period of frenetic and eclectic reforms, some more radical and others more traditional, under monarchs such as Edward VI and Elizabeth I, and Archbishops of Canterbury such as Thomas Cranmer and William Laud. What emerged was a state church that considered itself both "Reformed" and "Catholic" but not "Roman" (and hesitated from the title "Protestant"), and other "unofficial" more radical movements such as the Puritans.