For centuries the Catholic Church was the only religious authority in Europe. This institution had a monopoly on interpreting scripture and developing doctrine or official teaching. Christians were obligated to believe the Church's teaching or face the possibility of being imprisoned, killed or thrown out of the Church.

Despite the fact the Catholic Church had so much power they still encountered resistance. In the 12th century, the theologian Peter Abelard made an enemy of Anselm of Canterbury by attempting to rationally explain the Trinity. In the 15th century, a reform-minded priest and philosopher named Jan Hus challenged the Church's teaching on the Eucharist among other things. In the case of Abelard, he was forced to live out his days in a monastery. Hus and thousands of his followers were burnt at the stake.

In the 16th century, during the Renaissance, a German monk named Martin Luther attempted to get the Church to reform itself. One of the problems reformers saw in the Church was how it made simple things overly complicated. Luther, like Hus, wanted to see the Church return to the simple teachings of Jesus as found in the gospels. The Church, for its part, did not respond favorably to Luther's requests. Since the Church refused to reform itself this set off a chain of events which led to a permanent split within the Church called the Protestant Reformation.