Jews and heretics were discriminated and prosecuted in European countries because of religious disloyalty.

the clashes between papal authority and kings

Avignon papacy in the Great Schism in the 14th Century

Martin V and his successors repudiated the idea of church councils. They concentrated on reviving and strengthening their power through military might and magnificent display while neglecting the moral obligations. (e.g. Popes sometimes focused on administrative reform and maximization of revenue instead of piety and pastoral care. Some even violated their vows of chastity and engaged in nepotism.)

Increased anti-clericalism by kings and lay people and the beginning of grassroots movements to change the church

unconscientious and poorly-educated priests

church courts monitored personal behavior, having the potential to split the communities and breed resentment

The Inquisition (punishments including burning, or auto-da-fe)

church taxes and the resultant worldliness of the church seems inappropriate

Heresy wanted to de-emphasize the role of hierarchy and the authoritarianism of the church, and increased the role of the laity.

Church reformers or Christian humanists (often writers) sought reform within the church; Erasmus, Nicolas de cuza

Martin Luther 1483-1546

indulgences; purgatory; faith and salvation were gifts from God; 95 theses

The three source of religious truth according to Catholicism: scripture, church tradition, and papal and conciliar decisions

After the visit to Rome in high Renaissance, Luther concluded the only sure guide to God's will was to be found in scripture. (sola scriptura)

The Bible should be translated in the vernacular in order for lay people to read.

There was no need for a professional or sacrosanct clergy to interpret the Bible. (the priesthood of all believers)

Any piece of religious dogma or practice without scriptural foundation should be rejected or abolished out of hand.

The church emphasize the performance of good works to merit grace. Luther, tortured by his won sense of sin convinced of the basic depravity of the human species, believed that human beings were so far below God's perfection that they could not hope to earn or win forgiveness for their sins or salvation in heaven.

John Calvin, 1509-1564

predestination

The reason why Protestant ideas survived:

The church hesitated.

The rise of literacy and the development of the printing press. (Johannes Gutenberg, ca. 1400-1468)

The support from the German princes and the protection from Frederick the wise, elector of Saxony