The subject discussed in this paper is one that will not be found in the text books, either architectural or theological, though it touches on both. Architecture is a human idea, a product of the human mind; it is not a creation of the fancy, not the deliberate design of the draughtsman, not the outcome of a moment's inspiration. Originating in the need of man for shelter it has been the most human of the arts, closely associated with human life and thought, advancing with human civilization, retrograding with man's backward steps. To a very great extent, though perhaps not wholly so, architecture is a correct index of man's mental, social, political and religious state. Certain political conditions will be followed by certain intellectual advancement, or vice versa as the case may be, and architecture will be developed in a proportionate degree. The present discussion is limited entirely to the manifestation of religious ideas in architecture, and especially in Christian architecture.