Prior to the Enlightenment religion was the dominant political force across Europe. The Catholic Church wielded tremendous spiritual authority during the Middle Ages, as evidenced by the powerful investiture controversy of the 11th century; even after the Renaissance, monarchs continued to use religion to legitimize their authority. However, the Enlightenment, sometimes called the Age of Reason, challenged the supremacy of religion in the political and social life of Europe.

The Catholic Church

During the Early Middle Ages, the Catholic Church, based in Rome, built up its spiritual and political power. In 496 Clovis, king of the Franks, converted to Catholicism and used the religion to unify his people. In 754 Pepin the Short donated the land that became the Papal States to the papacy after the pope officially legitimized him as king. The fact that religion was so often used to legitimize a ruler shows its power during this time.

The Investiture Controversy

The Catholic Church cemented its power in the 11th century with the investiture controversy. Until the 11th century, church officials were appointed not by the pope but by kings who took bribes, a practice known as simony. Pope Gregory VII banned simony in 1075, and when Holy Roman Emperor Henry IV continued the practice, Gregory excommunicated him and declared his rule illegitimate, and in doing so instigated a rebellion against him by German princes. Without the pope's spiritual authority, Henry's power was considered meaningless.

Absolute Monarchy

Even when the Middle Ages had come to an end with the Renaissance, religion still held tremendous power in the political world of Europe. Many monarchs took more absolute control over their subjects and used religion to justify their increased authority, declaring that as kings they had a divine right to rule absolutely. The most famous such king was Louis XIV of France, who ruled France as an absolute monarch for 72 years.

The Enlightenment

With the Enlightenment, religion's domination over the political landscape of Europe ended. The Enlightenment, or Age of Reason, was the product of the scientific revolution of the 1600s and the ideas of a new group of philosophers including Voltaire, Rousseau and Locke, who viewed religion with skepticism. And though religion would not be wholly separated from politics, the Enlightenment's rationality would be at least partly responsible for revolutions in America in 1776 and France in 1789.