Objection 1. It would seem that religion is a theological virtue. Augustine says (Enchiridion iii) that "God is worshiped by faith, hope and charity," which are theological virtues. Now it belongs to religion to pay worship to God. Therefore religion is a theological virtue.
Objection 2. Further, a theological virtue is one that has God for its object. Now religion has God for its object, since it directs us to God alone, as stated above (Article 1). Therefore religion is a theological virtue.
Objection 3. Further, every virtue is either theological, or intellectual, or moral, as is clear from what has been said (I-II, 57,58,62). Now it is evident that religion is not an intellectual virtue, because its perfection does not depend on the consideration of truth: nor is it a moral virtue, which consists properly in observing the mean between too much and too little. for one cannot worship God too much, according to Sirach 43:33, "Blessing the Lord, exalt Him as much as you can; for He is above all praise." Therefore it remains that it is a theological virtue.
On the contrary, It is reckoned a part of justice which is a moral virtue.
I answer that, As stated above (Article 4) religion pays due worship to God. Hence two things are to be considered in religion: first that which it offers to God, viz. worship, and this is by way of matter and object in religion; secondly, that to which something is offered, viz. God, to Whom worship is paid. And yet the acts whereby God is worshiped do not reach out to God himself, as when we believe God we reach out to Him by believing; for which reason it was stated (1, 1 and 2 and 4) that God is the object of faith, not only because we believe in a God, but because we believe God.
Now due worship is paid to God, in so far as certain acts whereby God is worshiped, such as the offering of sacrifices and so forth, are done out of reverence for God. Hence it is evident that God is related to religion not as matter or object, but as end: and consequently religion is not a theological virtue whose object is the last end, but a moral virtue which is properly about things referred to the end.
Reply to Objection 1. The power or virtue whose action deals with an end, moves by its command the power or virtue whose action deals with matters directed to that end. Now the theological virtues, faith, hope and charity have an act in reference to God as their proper object: wherefore, by their command, they cause the act of religion, which performs certain deeds directed to God: and so Augustine says that God is worshiped by faith, hope and charity.
Reply to Objection 2. Religion directs man to God not as its object but as its end.
Reply to Objection 3. Religion is neither a theological nor an intellectual, but a moral virtue, since it is a part of justice, and observes a mean, not in the passions, but in actions directed to God, by establishing a kind of equality in them. And when I say "equality," I do not mean absolute equality, because it is not possible to pay God as much as we owe Him, but equality in consideration of man's ability and God's acceptance.
And it is possible to have too much in matters pertaining to the Divine worship, not as regards the circumstance of quantity, but as regards other circumstances, as when Divine worship is paid to whom it is not due, or when it is not due, or unduly in respect of some other circumstance.
Source: Summa Theologica (New Advent)