Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 19

Chapter 19.—On the Reasonableness of Offering, as the True Religion Teaches, a Visible Sacrifice to the One True and Invisible God.

As to those who think that these visible sacrifices are suitably offered to other gods, but that invisible sacrifices, the graces of purity of mind and holiness of will, should be offered, as greater and better, to the invisible God, Himself greater and better than all others, they must be oblivious that these visible sacrifices are signs of the invisible, as the words we utter are the signs of things.  And therefore, as in prayer or praise we direct intelligible words to Him to whom in our heart p. 193 we offer the very feelings we are expressing, so we are to understand that in sacrifice we offer visible sacrifice only to Him to whom in our heart we ought to present ourselves an invisible sacrifice.  It is then that the angels, and all those superior powers who are mighty by their goodness and piety, regard us with pleasure, and rejoice with us and assist us to the utmost of their power.  But if we offer such worship to them, they decline it; and when on any mission to men they become visible to the senses, they positively forbid it.  Examples of this occur in holy writ.  Some fancied they should, by adoration or sacrifice, pay the same honor to angels as is due to God, and were prevented from doing so by the angels themselves, and ordered to render it to Him to whom alone they know it to be due.  And the holy angels have in this been imitated by holy men of God.  For Paul and Barnabas, when they had wrought a miracle of healing in Lycaonia, were thought to be gods, and the Lycaonians desired to sacrifice to them, and they humbly and piously declined this honor, and announced to them the God in whom they should believe.  And those deceitful and proud spirits, who exact worship, do so simply because they know it to be due to the true God.  For that which they take pleasure in is not, as Porphyry says and some fancy, the smell of the victims, but divine honors.  They have, in fact, plenty odors on all hands, and if they wished more, they could provide them for themselves.  But the spirits who arrogate to themselves divinity are delighted not with the smoke of carcasses but with the suppliant spirit which they deceive and hold in subjection, and hinder from drawing near to God, preventing him from offering himself in sacrifice to God by inducing him to sacrifice to others.