A well-known Roman Catholic review recently observed that modernism is not merely an internal difficulty of the Catholic church, but that the Protestant and Jewish bodies are likewise tormented and undermined by it. And the remark is certainly correct. For if, on the one hand, modernism tends to apply to the internal discipline and rites of the Roman church many of those reforms which the Protestants adopted from the beginning of the Reformation,—reforms rendered necessary by the changed conditions of the times, and today even more necessary than ever, —on the other hand it is profoundly modifying the very concept of revelation and making more and more difficult every kind of stability of doctrine and every regula fidei; so that Christianity itself, and the Jewish religion from which it comes, are to a large extent challenged by it and are in a measure associated with the church of Rome in one common defence. This defence, so far as it has any probability of success, thus tends to change not only the relation of these religions to the spirit of contemporary thought, but even their inter-relations, constraining them to abandon one or another of those positions which caused dissension and associating them under the protection of their common spiritual inheritance. Hence it will be worth while to consider briefly what conclusions are suggested by the most recent experience in this controversy, and what forecast we can make, not so much for the future of the individual churches as for a future of much greater interest, that, namely, of Christianity itself and of the religious consciousness among the nations of western civilization.