Rev José Mario O Mandía
The first commandment also calls us to practice the virtue of religion. The virtue of religion is not a theological virtue. Rather, it is one of the moral virtues that falls under the virtue of justice (BST 188). When we hear the word “justice,” we often think of what we ought to give to others. But the first “other” is God. The virtue of religion reminds us of our duty of justice towards God – our Creator, our Redeemer, and our Sanctifier. This is why the virtue of religion falls under the first commandment.
The CCC (no 2095) thus says: “The theological virtues of faith, hope, and charity inform and give life to the moral virtues. Thus, charity leads us to render to God what we as creatures owe him in all justice. The virtue of religion disposes us to have this attitude.”
Jesus was referring to the virtue of religion when he said, “Adore the Lord your God and worship Him alone” (Matthew 4:10).
What specific acts do we owe God? The CCCC 443 explains: “These words mean  to adore God as the Lord of everything that exists;  to render to him the individual and community worship which is his due;  to pray to him with sentiments of praise, of thanks, and of supplication;  to offer him sacrifices, above all the spiritual sacrifice of one’s own life, united with the perfect sacrifice of Christ; and  to keep the promises and vows made to him.”
The CCCC (no 444) adds: “Every person has the right and the moral duty to seek the truth, especially in what concerns God and his Church. Once the truth is known, each person has the right and moral duty to embrace it, to guard it faithfully and to render God authentic worship. At the same time, the dignity of the human person requires that in religious matters no one may be forced to act against conscience nor be restrained, within the just limits of public order, from acting in conformity with conscience, privately or publicly, alone or in association with others.”
The first commandment also teaches us what we should avoid. “You shall not have other gods before me” (Exodus 20:2). CCCC 445 lists the sins against the virtue of religion. “This commandment forbids:
(1) Polytheism and idolatry, which divinizes creatures, power, money, or even demons.
(2) Superstition which is a departure from the worship due to the true God and which also expresses itself in various forms of divination, magic, sorcery and spiritism.
(3) Irreligion which is evidenced: in tempting God by word or deed; in sacrilege, which profanes sacred persons or sacred things, above all the Eucharist; and in simony, which involves the buying or selling of spiritual things.
(4) Atheism which rejects the existence of God, founded often on a false conception of human autonomy.
(5) Agnosticism which affirms that nothing can be known about God, and involves indifferentism and practical atheism.
The commandment also says, “You shall not make for yourself a graven image” (Exodus 20:3). Does that mean we cannot make religious statues and paintings? The CCCC 446 clarifies the difference between the Old and the New Law. “In the Old Testament this commandment forbade any representation of God who is absolutely transcendent. The Christian veneration of sacred images, however, is justified by the incarnation of the Son of God (as taught by the Second Council of Nicea in 787 AD) because such veneration is founded on the mystery of the Son of God made man, in whom the transcendent God is made visible. This does not mean the adoration of an image, but rather the veneration of the one who is represented in it: for example, Christ, the Blessed Virgin Mary, the Angels and the Saints.”