Almost all the changes which the world has undergone since the end of the Middle Ages are due to the discovery and diffusion of new knowledge. This was the primary cause of the Renaissance, the Reformation, and the industrial revolution. It was also, very directly, the cause of the decay of dogmatic religion. The study of classical texts and early Church history, Copernican astronomy and physics, Darwinian biology and comparative anthropology, have each in turn battered down some part of the edifice of Catholic dogma, until, for almost all thinking and instructed people, the most that seems defensible is some inner spirit, some vague hope, and some not very definite feeling of moral obligation. This result might perhaps have remained limited to the educated minority but for the fact that the Churches have almost everywhere opposed political progress with the same bitterness with which they have opposed progress in thought. Political conservatism has brought the Churches into conflict with whatever was vigorous in the working classes, and has spread free thought in wide circles which might otherwise have remained orthodox for centuries. The decay of dogmatic religion is, for good or evil, one of the most important facts in the modern world. Its effects have hardly yet begun to show themselves: what they will be it is impossible to say, but they will certainly be profound and far-reaching.
Religion is partly personal, partly social: to the Protestant primarily personal, to the Catholic primarily social. It is only when the two elements are intimately blended that religion becomes a powerful force in molding society. The Catholic Church, as it existed from the time of Constantine to the time of the Reformation, represented a blending which would have seemed incredible if it had not been actually achieved, the blending of Christ and Cæsar, of the morality of humble submission with the pride of Imperial Rome. Those who loved the one could find it in the Thebaid; those who loved the other could admire it in the pomp of metropolitan archbishops. In St. Francis and Innocent III the same two sides of the Church are still represented. But since the Reformation personal religion has been increasingly outside the Catholic Church, while the religion which has remained Catholic has been increasingly a matter of institutions and politics and historic continuity. This division has weakened the force of religion: religious bodies have not been strengthened by the enthusiasm and single-mindedness of the men in whom personal religion is strong, and these men have not found their teaching diffused and made permanent by the power of ecclesiastical institutions.