God can be honoured by man, both in body and in spirit; and, therefore, religion must be both interior and exterior. Interior worship is paid to God by means of the understanding and the will; and exterior homage by means of ceremonies and sacrifices.

Interior religion, then, strictly speaking, signifies uprightness of heart before God, and perfection of life. For, as every effect honours its cause chiefly by its perfection, man cannot pay to God a greater homage than that of a perfect life. This, therefore, constitutes the truth and completeness of Divine worship, even as the perfection of a work gives glory to the worker.

And, as we pay homage to God, not only in order to honour Him, but also in order to receive beatitude from Him; and as a good life is a more sure way of attaining to beatitude than are sacrifices and ceremonies, it is evident that perfection of life is a more true religion than any exterior form of worship. God is not a body, but Pure Act: therefore man renders to Him more perfect worship by purity of heart, than by external actions, for “God is a Spirit, and they that adore Him, must adore Him in spirit and in truth” (St. John iv. 24).