(3) To Christian Theology, or revealed religion. As this is the fullest disclosure of the duty of man, in all his relations, to God, to his fellow-men, and to his own end, it is not surprising that for so many centuries, the treatment of morals was made simply a part of general theology, and merely distinguished as Moral Theology. In the modern separation of ethics from theology and treatment of it as a science, it is not meant to deny the close affinity between the two investigations or the rich illumination that duty receives from supernatural revelation, but only to trace out more distinctly and fully, in independent and scientific form, the deep and immovable foundations of the principles of duty in the very constitution of man and the world. This exhibition of the natural basis of ethical law and obligation becomes an independent and generic enforcement of the principles of righteousness. It gives a philosophic vindication of one of the first assumptions of Christianity--the supremacy of the law of rectitude for human life. And Christianity is vindicated and exalted when it comes recognizing and confirming all the principles and duties discoverable in our moral nature, and adding a supernatural disclosure of the way in which righteousness may be established in our lives, and men may attain their right character and destiny.
Christianity, while much more than this, appears as a divine re-publication of the ethical truth which from the first has been incorporated in the organization of humanity. In it the light of conscience is supplemented and made clear. The ethics of human reason and those of revelation thus cover, to a great extent, the same ground. When correctly read they are never in conflict, but in harmony. Both show man to be under moral law--and under broken law, that is, under sin. But the light of the Scriptures is broader and fuller. For in addition to their confirmation of a natural ethic for man, they disclose a scheme of redemption, with otherwise undiscoverable moral relations and obligations, introducing new and vital elements into the science of ethics. The inclusion of these elements and truths turns pagan or natural ethics into Christian.