If we compare Christianity with the other dogmatic religions of the world, we are at once struck by a feature peculiar to it, namely, the complexity of its doctrinal system. A glance at the Athanasian Creed is sufficient to show that this peculiarity results from the existence of fundamental inconsistencies in the dogmas of Christianity. Such inconsistencies are not found in other religions, whether, like Mohammedanism, they have at once sprung into full maturity at the time of their creation, or whether, like Judaism, they have passed through a long and slow process of development. The inconsistencies of Christian doctrine clearly cannot be ascribed to the necessary tendencies of the evolution of dogmatic religion; they must be due to special circumstances connected with the history of Christianity.

What these circumstances were there is no difficulty in ascertaining. The fully developed dogmatic system of Christianity is the product of the union of two opposite streams of religious tendency. From the collision of the monotheism of Judaism with the polytheism of Paganism the inconsistencies of its doctrines have sprung. In the doctrine of the Trinity, which takes up so much of the Athanasian Creed, we have the clearest evidence of this. But, in reality, the whole of Christianity is pervaded by the contradictions inseparable from the combination in it of the characteristics of monotheistic and polytheistic religion. This combination is the source of its unique power; it thus can satisfy both the higher and the lower class of religious instincts; but its complex and confused theology is also an inevitable result.

The distinctive feature of the doctrinal system of Christianity can thus be readily explained by a reference to the conditions of its origin. To investigate in detail, by the same method of historical inquiry, the causes which produced its separate dogmas, is the object of this essay. The origin of the earlier ones must be traced through the history of Judaism; the later ones were Pagan, but they were grafted on a Jewish stock. Starting from primary religious ideas, we have to examine the growth and modification of theological dogma. Our study, accordingly, will take us over the whole period of history.