Objection 1. It would seem that religion is not one virtue. Religion directs us to God, as stated above (Article 1). Now in God there are three Persons; and also many attributes, which differ at least logically from one another. Now a logical difference in the object suffices for a difference of virtue, as stated above (50, 2, ad 2). Therefore religion is not one virtue.
Objection 2. Further, of one virtue there is seemingly one act, since habits are distinguished by their acts. Now there are many acts of religion, for instance to worship, to serve, to vow, to pray, to sacrifice and many such like. Therefore religion is not one virtue.
Objection 3. Further, adoration belongs to religion. Now adoration is paid to images under one aspect, and under another aspect to God Himself. Since, then, a difference of aspect distinguishes virtues, it would seem that religion is not one virtue.
On the contrary, It is written (Ephesians 4:5): "One God [Vulgate: 'Lord'], one faith." Now true religion professes faith in one God. Therefore religion is one virtue.
I answer that, As stated above (I-II, 54, 2, ad 1), habits are differentiated according to a different aspect of the object. Now it belongs to religion to show reverence to one God under one aspect, namely, as the first principle of the creation and government of things. Wherefore He Himself says (Malachi 1:6): "If... I be a father, where is My honor?" For it belongs to a father to beget and to govern. Therefore it is evident that religion is one virtue.
Reply to Objection 1. The three Divine Persons are the one principle of the creation and government of things, wherefore they are served by one religion. The different aspects of the attributes concur under the aspect of first principle, because God produces all things, and governs them by the wisdom, will and power of His goodness. Wherefore religion is one virtue.
Reply to Objection 2. By the one same act man both serves and worships God, for worship regards the excellence of God, to Whom reverence is due: while service regards the subjection of man who, by his condition, is under an obligation of showing reverence to God. To these two belong all acts ascribed to religion, because, by them all, man bears witness to the Divine excellence and to his own subjection to God, either by offering something to God, or by assuming something Divine.
Reply to Objection 3. The worship of religion is paid to images, not as considered in themselves, nor as things, but as images leading us to God incarnate. Now movement to an image as image does not stop at the image, but goes on to the thing it represents. Hence neither "latria" nor the virtue of religion is differentiated by the fact that religious worship is paid to the images of Christ.
Source: Summa Theologica (New Advent)