Q. 1. What is the First Commandment and what sin does it condemn?
A. 1. The First Commandment is, "I am the Lord your God; you shall not have strange gods before Me."
The First Commandment forbids us to adore false gods. It forbids us to give to anyone or anything the adoration and service that belongs to God alone. It forbids us to adore God by false worship.
The First Commandment forbids us to call Mary "Divine." While the Blessed Virgin Mary is the Mother of God, being Holy, she is not Divine. The word "Divine" is reserved to God alone. While one may pray to Jesus through Mary, one may never pray to Mary with the understanding that she is the one who grants Divine favours.
When pagans and idolators worship false gods, they break the First Commanment. That includes the irreligious, the uncivilized, the unenlightened, the unconverted, those who reject the God of Judaism and Christianity.
By attributing to persons or things powers that belong to God alone, you break the First Commandment. Example: Believing in the power of fortune tellers to reveal the future, or in the power of spiritualists to bring back the dead or to bring messages from the dead, or in the power of charms to avert evil or to bring “good luck..”
You breach the First Commandment when you wilfully belong to a religion or a church which is known not to be the True Church established by Jesus Christ. Also by considering all religions as being equal, especially in the area of the Sacrament of the Holy Eucharist. What difference is there between receiving the Sacrament of the Holy Eucharist in the Catholic Church versus receiving the bread from another religion? Only the Holy Catholic Church recognizes the permanent Real Presence of Jesus in the Holy Eucharist once the bread has been consecrated during the Holy Mass.
What does the First Commandment teach us about divination and magic? God can reveal the future to his prophets or to other saints. Still, a sound Christian attitude consists in putting oneself confidently into the hands of Providence for whatever concerns the future, and giving up all unhealthy curiosity about it. Improvidence, however, can constitute a lack of responsibility. (C.C.C. # 2115) All forms of divination are to be rejected: recourse to Satan or demons, conjuring up the dead or other practices falsely supposed to "unveil" the future. [Cf. Deut 18:10; Jer 29:8] Consulting horoscopes, astrology, palm reading, interpretation of omens and lots, the phenomena of clairvoyance, and recourse to mediums all conceal a desire for power over time, history, and, in the last analysis, other human beings, as well as a wish to conciliate hidden powers. They contradict the honor, respect, and loving fear that we owe to God alone. (C.C.C. # 2116)
All practices of magic or sorcery, by which one attempts to tame occult powers, so as to place them at one's service and have a supernatural power over others - even if this were for the sake of restoring their health - are gravely contrary to the virtue of religion. These practices are even more to be condemned when accompanied by the intention of harming someone, or when they have recourse to the intervention of demons. Wearing charms is also reprehensible. Spiritism often implies divination or magical practices; the Church for her part warns the faithful against it. Recourse to so-called traditional cures does not justify either the invocation of evil powers or the exploitation of another's credulity. (C.C.C. # 2117)
Why are we commanded to adore God? Because God is the Creator and Ruler of the whole world, and because all we have we received from God. [“Jesus said to him, ‘Away with you, Satan! For it is written, ‘Worship the Lord your God, and serve only Him.’‘” Mt. 4:10] How do we show our adoration of God? By offering Him our humble prayers, and especially by the Holy sacrifice of the Mass. Is the practice of religion necessary, then, for everyone? It is certainly necessary for everyone, and those who say it is enough to lead a good moral life without practicing religion are failing to keep this First Commandment. (What they are saying in their own words is, “My way is better than God’s way!”)
The first commandment is also concerned with sins against hope, namely, despair and presumption: By despair, man ceases to hope for his personal salvation from God, for help in attaining it or for the forgiveness of his sins. Despair is contrary to God's goodness, to his justice - for the Lord is faithful to his promises - and to his mercy. (C.C.C. # 2091)
There are two kinds of presumption. Either man presumes upon his own capacities, (hoping to be able to save himself without help from on high), or he presumes upon God's almighty power or his mercy (hoping to obtain his forgiveness without conversion and glory without merit). (C.C.C. # 2092)
Do Catholics break the First Commandment by having crucifixes and statues in their churches? No, because they do not adore these. God does not forbid the mere making of images, but the adoring of them after they are made: “You shall not bow down to them or worship them.” [Exo. 20:5]
Note: In the same Book of the Holy Bible where we find the Commandments, we have the record of God commanding the making of the images of two Angels: “You shall make two cherubim of gold; you shall make them of hammered work, at the two ends of the mercy seat.” i.e., the ark of the covenant. [Exo. 25:18]