Objection 1. It would seem that sacrifice should not be offered to the most high God alone. Since sacrifice ought to be offered to God, it would seem that it ought to be offered to all such as are partakers of the Godhead. Now holy men are made "partakers of the Divine nature," according to 2 Peter 1:4; wherefore of them is it written (Psalm 81:6): "I have said, You are gods": and angels too are called "sons of God," according to Job 1:6. Thus sacrifice should be offered to all these.
Objection 2. Further, the greater a person is the greater the honor due to him from man. Now the angels and saints are far greater than any earthly princes: and yet the subjects of the latter pay them much greater honor, by prostrating before them, and offering them gifts, than is implied by offering an animal or any other thing in sacrifice. Much more therefore may one offer sacrifice to the angels and saints.
Objection 3. Further, temples and altars are raised for the offering of sacrifices. Yet temples and altars are raised to angels and saints. Therefore sacrifices also may be offered to them.
On the contrary, It is written (Exodus 22:20): "He that sacrificeth to gods shall be put to death, save only to the Lord."
I answer that, As stated above (Article 1), a sacrifice is offered in order that something may be represented. Now the sacrifice that is offered outwardly represents the inward spiritual sacrifice, whereby the soul offers itself to God according to Psalm 50:19, "A sacrifice to God is an afflicted spirit," since, as stated above (81, 07; 84, 2), the outward acts of religion are directed to the inward acts. Again the soul offers itself in sacrifice to God as its beginning by creation, and its end by beatification: and according to the true faith God alone is the creator of our souls, as stated in I, 90, 3; I-II, 118, 2, while in Him alone the beatitude of our soul consists, as stated above (I-II, 01, 8; I-II, 2, 8; I-II, 3, 1 and 7 and 8). Wherefore just as to God alone ought we to offer spiritual sacrifice, so too ought we to offer outward sacrifices to Him alone: even so "in our prayers and praises we proffer significant words to Him to Whom in our hearts we offer the things which we designate thereby," as Augustine states (De Civ. Dei x, 19). Moreover we find that in every country the people are wont to show the sovereign ruler some special sign of honor, and that if this be shown to anyone else, it is a crime of high-treason. Therefore, in the Divine law, the death punishment is assigned to those who offer Divine honor to another than God.
Reply to Objection 1. The name of the Godhead is communicated to certain ones, not equally with God, but by participation; hence neither is equal honor due to them.
Reply to Objection 2. The offering of a sacrifice is measured not by the value of the animal killed, but by its signification, for it is done in honor of the sovereign Ruler of the whole universe. Wherefore, as Augustine says (De Civ. Dei x, 19), "the demons rejoice, not in the stench of corpses, but in receiving divine honors."
Reply to Objection 3. As Augustine says (De Civ. Dei viii, 19), "we do not raise temples and priesthoods to the martyrs, because not they but their God is our God. Wherefore the priest says not: I offer sacrifice to thee, Peter or Paul. But we give thanks to God for their triumphs, and urge ourselves to imitate them."
Source: Summa Theologica (New Advent)