He does not spend time discussing various religions in detail, but deals with them briefly in general, in order to show that the Christian religion is far superior to all other religions, then he makes a critical and very able examination of the Christian position. He considers it necessary to discuss in detail only that form of religion that is undoubtedly the highest.
The historical religions he finds to be of two types—religions of law and religions of redemption. The religions of law portray God as a being outside the world, and distinct from man, One who rules the world by law, and who decrees that man shall obey certain laws of conduct that He lays down. Failure to obey these laws brings its punishment in the present or in a future life, while implicit obedience brings the highest rewards. To such a God is often attributed all the weaknesses of the human being, sometimes in a much exaggerated form—hence His reign becomes one of fear to His subjects.
A religion of law assumes that man is capable of himself of obeying the law, and is responsible for his mode of life; it assumes that man is capable through his own energy of conquering the world of sin, and of leading the higher life.
Religions of this type possess of course the merit of simplicity, transparency, and finality. The decrees, the punishments and rewards are given with some clearness and are easily understood; there is no appeal and little equivocation. They served a useful purpose in the earlier ages of civilisation, but cannot solve the problem for the complex civilisation and advanced culture of the present age. They place God too far from man, and attribute to man powers which he cannot of himself possess. The conceptions of the Deity involved in them are too anthropomorphic in character—too much coloured by human frailties.
The religions of law have had to give place to those of a superior type—the religions of redemption. These religions appreciate the difficulty there exists for humankind of itself to transcend the world of sin, and are of two types—one type expressing a merely negative element, the other a negative and positive element.
The typical negative redemptive religion is that of Buddhism. Buddhism teaches us that the world is a sham and an evil; and the duty of man is to appreciate this fact, and to deny the world, but here the matter ends—it ends with world-renunciation and self-renunciation. There is only a negative element in such a religion, no inspiration to live and fight for gaining a higher world. This, of course, cannot provide a satisfactory solution to the problem, for no new life with new values is presented to us. It is a religion devoid of hope, for it does not point to a higher life. "A wisdom of world-denial, a calm composure of the nature, an entire serenity in the midst of the changing scenes of life, constitute the summit of life."
Christianity teaches us that the world is full of misery and suffering, but the world in itself is really a perfect work of Divine wisdom and goodness. "The root of evil is not in the nature of the world, but in moral wrong—in a desertion from God." Sin and wickedness arise from the misuse and perversion of things which are not in themselves evil. Christianity calls for a break from the wickedness of the world. It calls upon man to give up his sin, to deny, or break with, the evil of which he is guilty. But it does not expect man to do this in his own strength alone—God Himself comes to his rescue. Unlike Buddhism, it does not stay at the denial of the world, but calls upon man to become a citizen of a higher world. This gives a new impetus to the higher life; man finds a great task—he has to build a kingdom of God upon the earth. This demands the highest efforts—he must fight to gain the new world, and must keep up the struggle to retain what he has gained. The inferiority of Buddhism as contrasted with Christianity is well described by Eucken in the following words: "In the former an emancipation from semblance becomes necessary; in the latter an overcoming of evil is the one thing needful. In the former the very basis of the world seems evil; in the latter it is the perversion of this basis which seems evil. In the former, the impulses of life are to be entirely eradicated; in the latter, on the contrary, they are to be ennobled, or rather to be transformed. In the former, no higher world of a positive kind dawns on man, so that life finally reaches a seemingly valid point of rest, whilst upon Christian ground life ever anew ascends beyond itself."
From such considerations as these, Eucken comes to the conclusion that of the redemptive religions, which are themselves the highest type, Christianity is the highest and noblest form, hence his main criticism is concerned with the Christian religion. This does not mean that he finds neither value nor truth in any other form of religion. His general conclusion with regard to the historical religions is that they "contain too much that is merely human to be valued as a pure work of God, and yet too much that is spiritual and divine to be considered as a mere product of man." He finds in them all some kernel of truth, or at least a pathway to some part of truth, but contends that no religion contains the whole truth and nothing but the truth. "As certainly," he says, "as there is only one sole truth, there can be only one absolute religion, and this religion coincides entirely in no way with any one of the historical religions."
Eucken's great endeavour in his discussion of the Christian religion is to bring out the distinction between the eternal substance that resides in it and the human additions that have been made to it in different ages, between the elements in Christianity that are essentially divine and those essentially human. Divested of its human colourings and accretions, Christianity presents a basis of Divine and eternal truth, and this regarded in itself, can well claim to be the final and absolute religion.
The conclusion he has come to with regard to the eternal truth as contrasted with the temporary colourings of Christianity, with the essential as contrasted with the inessential, can best be outlined by taking in turn some of the main tenets and characteristics of the Christian faith.