The context of the Reformation was the strange state of the Catholic Church as of the late fifteenth century. the Church was omnipresent in early-modern European society. About one person in seventy-five was part of the Church, as priests, monks, nuns, or members of lay orders. Practically every work of art depicted Biblical themes. the Church oversaw births, marriages, contracts, wills, and deaths - all law was, by implication, the law of God Himself. Furthermore, in Catholic doctrine, spiritual salvation was only accessible through the intervention of the Church; without the rituals (sacraments) performed by priests, the soul was doomed to go to hell. Finally, popes fought to claim the right to intervene in secular affairs as they saw fit, although this was a fight they had never had much luck with, losing even more ground as the new, more powerful and centralized, monarchies rose to power in the fifteenth century.
Simply put, as of the Renaissance era, all was not well with the Church. The Babylonian Captivity and the Great Western Schism both undermined the Church’s authority. The stronger states of the period claimed the right to appoint bishops and priests within their kingdoms, something that the monarchs of England and France were very successful in doing. This led both laypeople and some priests themselves to look to monarchs, rather than the pope, for patronage and authority.
At the same time, elite churchmen (including the popes themselves) continued to live like princes. The papacy not only set a bad example, but attempts to reform the lifestyles and relative piety of priests generally failed; the papacy was simply too remote from the everyday life of the priesthood across Europe, and since elite churchmen were all nobles, they usually continued to live like nobles. In many cases, they openly lived with concubines, had children, and worked to ensure that their children receive lucrative positions in the Church. Laypeople were well aware of the slack morality that pervaded the Church. Medieval and early-modern literature is absolutely shot through with satirical tracts mocking immoral priests, and depictions of hell almost always featured priests, monks, and nuns burning alongside nobles and merchants.
These patterns affected monasticism as well. The idea behind monastic orders had been imitating the life of Christ, yet by the early modern period, many monasteries (especially urban ones) ran successful industries, and monks often lived in relative luxury compared to townspeople. Furthermore, the monasteries had been very successful in buying up or receiving land as gifts; by the late fifteenth century a full 20% of the land of the western kingdoms was owned by monasteries. The contrast between the required vow of poverty taken by monks and nuns and the wealth and luxury many monks and nuns enjoyed was obvious to laypeople.
The result of this widespread concern with corruption was a new focus on the inner spiritual life of the individual, not the focus on and respect for the priest, monk, or nun. New movements sprung up around Europe, including one called Modern Devotion in the Netherlands, that focused on moral and spiritual life of laypeople outside of the auspices of the Church. The handbook of the Modern Devotion was called The Imitation of Christ, written in the mid-fifteenth century and published in various editions after that, which was so popular that its sales matched those of the Bible at the time. It promoted the idea of salvation without needing the Church as an intermediary at all.
Within the Church, there were widespread and persistent calls for reform to better address the needs of the laity and to better live up to the Church’s own moral standards. Numerous devout priests, monks, and nuns abhorred the corruption of their peers and superiors in the Church and called for change - the Spanish branch of the Church enjoyed a strong period of reform during the fifteenth century, for example. Despite this reforming zeal within the Church and the growing popularity of lay movements outside of it, however, almost no one anticipated a permanent break from the Church’s hierarchy itself.