From Pope St. John Paul II’s encyclical Fides et Ratio (1984):
The more influential of these radical positions are well known and high in profile, especially in the history of the West. It is not too much to claim that the development of a good part of modern philosophy has seen it move further and further away from Christian Revelation, to the point of setting itself quite explicitly in opposition. This process reached its apogee in the last century. Some representatives of idealism sought in various ways to transform faith and its contents, even the mystery of the Death and Resurrection of Jesus, into dialectical structures which could be grasped by reason. Opposed to this kind of thinking were various forms of atheistic humanism, expressed in philosophical terms, which regarded faith as alienating and damaging to the development of a full rationality. They did not hesitate to present themselves as new religions serving as a basis for projects which, on the political and social plane, gave rise to totalitarian systems which have been disastrous for humanity.
In the field of scientific research, a positivistic mentality took hold which not only abandoned the Christian vision of the world, but more especially rejected every appeal to a metaphysical or moral vision. It follows that certain scientists, lacking any ethical point of reference, are in danger of putting at the centre of their concerns something other than the human person and the entirety of the person’s life. Further still, some of these, sensing the opportunities of technological progress, seem to succumb not only to a market-based logic, but also to the temptation of a quasi-divine power over nature and even over the human being.
As a result of the crisis of rationalism, what has appeared finally is nihilism. As a philosophy of nothingness, it has a certain attraction for people of our time. Its adherents claim that the search is an end in itself, without any hope or possibility of ever attaining the goal of truth. In the nihilist interpretation, life is no more than an occasion for sensations and experiences in which the ephemeral has pride of place. Nihilism is at the root of the widespread mentality which claims that a definitive commitment should no longer be made, because everything is fleeting and provisional.
— Fides et Ratio 46