Theology and religion involve intimately related conceptions of the world, its make-up, and its causes. Strictly speaking, religion is a system of piety and worship, while theology deals more particularly with the ultimate and supernatural powers conceived in one way or another as the God and the gods who have constructed the universe and have subsequently ordered its happenings. A religion is a group of ideas having the effect of motives; it is dynamic and directs human conduct. Theology, on the other hand, is more theoretical and descriptive, and its conceptions, together with those of other departments of human thought, give the materials for the formulation of the religious beliefs which determine the attitudes of men toward all of the great universe in which they play their part and whose mysteries they attempt to solve.
Defined and distinguished in these ways, these two departments of higher human life present themselves for comparative study and historic explanation. They differ much among the varied races of mankind, so much, indeed, that an investigator who approaches their study with a knowledge only of Christian religion and theology finds it difficult at first to recognize that the same fundamental ideas, although of far cruder nature, enter into the conceptions of an idol-worshiping fanatic living in the heart of Africa. But, nevertheless, beliefs that fall within the scope of the definitions adopted above are to be found among all men, and they must be examined so that their agreements and differences may be demonstrated, and their common elements may be explained as the natural products of a process of evolution.
Such a broad comparative study, like that of physical, mental, and social phenomena discussed heretofore, must be conducted objectively; that is, each and every particular belief of a religious or theological nature which can be discovered in any race is entitled to a place in the array of materials which demand scientific treatment. They must be verified, classified, and summarized, in order that their total meaning and value can be discovered. It must be strongly emphasized that for such purposes the inherent validity and truth or falsity of diverse religions are not called into question when they are so considered as objects of study; many still entertain the view that the mere task of conducting an analysis of a group of religious beliefs of whatever nature must tend to destroy or alter that system of religion in some way and degree. But whatever the comparative student may himself believe, the conception of Jehovah in the Hebrew religion is quite as legitimate an object of study as the Buddhistic concept of Brahma as the Ultimate Being, or the Polynesian idea of Tangaroa as the god of the waves. We would naturally be inclined to exclude the last from our own personal system of piety and worship as the childish concept of an imaginative, adolescent race; but whatever the truth may be, the