The Church was affected in largely positive ways by the Age of Discovery, as it found itself confronted, for the first time in many centuries, with whole societies of people who had never heard of Christ. Henceforth modern Christianity would be characterized, increasingly, by a global perspective. Originally there was debate as to whether the "Indians" and others should be considered human beings, but very quickly Church authorities decreed that they were and that therefore they ought to be evangelized.
Especially in the Far East, the new discoveries posed a long-term challenge to the Church, in that the missionaries found themselves confronting very ancient, very sophisticated civilizations which could not simply be treated as primitive. Here, especially in the person of certain Jesuits, the Church for the first time in centuries confronted the issue which would later be called "inculturation" -- how the Gospel can be incarnated in a culture very different from that of the West.
At the same time these missionaries never lost sight of the fact that they were preaching the one true faith. In later centuries, however, that issue became a key one for modernist Christians, who would draw the conclusion that non-Christian religions must be treated as paths to God equally as valid with Christianity itself.
The great blow to the Church at the beginning of modern times was of course the Protestant Reformation, which split the unity of Christendom for all times and destroyed the Church's authority in half of Europe. For a generation the Church reeled under a series of blows and appeared unable to resist. Then, beginning around 1540, the Counter-Reformation (now often called the Catholic Reformation) began, regaining some of the territory which the Church had lost, not just in geographical terms but in terms of authority and credibility.
Although sometimes thought of as the preservation of the Middle Ages, the Catholic Reformation was in fact a new, distinctively modern chapter in the history of the Church, in such things as "radical" conceptions of religious life (the Jesuits) and systematic programs of catechizing and evangelizing in ways never before attempted, and a daring new style of religious art -- the Baroque.
The spirit of the Catholic Reformation came to be thought of as one of stern orthodoxy and morality, deep personal piety, and obedience to Church authority. This revival was profoundly successful, and it gave the modern Church the form in which it continued until around 1960.
Both the Age of Discovery and the Protestant Reformation brought the Church into the modern world in the sense that both phenomena forced Catholics to see their Church in the context of other faiths, to be able to affirm their beliefs in the face of doubt.
Despite the Galileo case and other such incidents, the Scientific Revolution posed no serious threat to the Church, except insofar as it gave rise to the tendency to exalt scientific knowledge above all other kinds, the full implications of which were not realized for over a century.
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