18 At the same time, two categories become increasingly central to the idea of progress: reason and freedom. Progress is primarily associated with the growing dominion of reason, and this reason is obviously considered to be a force of good and a force for good. Progress is the overcoming of all forms of dependency—it is progress towards perfect freedom. Likewise freedom is seen purely as a promise, in which man becomes more and more fully himself. In both concepts—freedom and reason—there is a political aspect. The kingdom of reason, in fact, is expected as the new condition of the human race once it has attained total freedom. The political conditions of such a kingdom of reason and freedom, however, appear at first sight somewhat ill defined. Reason and freedom seem to guarantee by themselves, by virtue of their intrinsic goodness, a new and perfect human community. The two key concepts of “reason” and “freedom”, however, were tacitly interpreted as being in conflict with the shackles of faith and of the Church as well as those of the political structures of the period. Both concepts therefore contain a revolutionary potential of enormous explosive force.
Source: Spe Salvi (Vatican.va)