Here, the first words are introductory to all the Ten Commandments, and "I am the Lord thy God" is said to show that we acknowledge that God, as our Lord and Creator, has the right to command what He wishes, and that we, His creatures, are bound to obey Him. By the words, "Thou shalt not have any other God but Me," God bids us acknowledge, adore, love and serve Him alone as our Supreme Lord.
This Commandment is fulfilled by the practice of inward and outward worship. Inward worship is the honor paid to God with the spirit only, or with the mind and will. Outward worship is homage given to God by means of outward acts and sensible things. It is not enough to worship God with the heart and inwardly alone, but He must be adored outwardly also, with the body as well as the soul, because He is the Creator and absolute Lord of the one as well as the other. Furthermore, it is quite impossible to divorce outward worship from the inward, because if the latter be separated from the former, then the former is robbed of life, merit and efficacy, like a body which is without a soul.
The First Commandment forbids idolatry, superstition, sacrilege, heresy and every sort of sin against religion. Idolatry is giving to any creature, for instance, to a statue, a picture or a man, the supreme worship of adoration due to God. This prohibition is found in Holy Scripture expressed in the following words: "Thou shalt not make to thyself a graven thing, nor the likeness of anything that is in heaven above or in the earth beneath, nor of those things that are in the waters under the earth. Thou shalt not adore them nor serve them." Yet it must not be supposed that these words forbid every sort of image; but only those of false divinities, made for the purpose of adoration, as were those of the idolaters. This is such an obvious truth that God Himself bade Moses to make some, such as the two statues of the Cherubim in the ark and the brazen serpent in the wilderness. Superstition is any devotion contrary to the teaching and custom of the Church, as, for instance, to attribute to any act or thing taken by itself a supernatural power which it does not possess. Sacrilege is the profanation of a place, person or thing consecrated to God and set apart for His worship. Heresy is a culpable error of the intellect, whereby some truth of the Faith is obstinately denied.
Furthermore, the First Commandment forbids any intercourse with evil spirits, and any association with anti-Christian sects. Whoever has recourse to the devil or invokes him commits a tremendous sin, because the devil is the most perverse of all the enemies of God and man. All the practices of spiritualism are unlawful, because they are superstitious, and frequently they are involved in demoniacal intervention, and therefore they are rightly prohibited by the Church.
This Commandment does not, however, forbid us to honor and invoke the Angels and Saints; but, on the contrary, we ought to do this, because it is a good and profitable thing to do, and it is highly recommended by the Church, since Saints and Angels are friends of God and are our intercessors with Him.
Although Jesus Christ is our only Mediator with God, we have recourse to the mediation of our Lady and the Saints, because Jesus Christ is our Mediator, as being both God and man, and He alone, in virtue of His own merits, has reconciled us with God, and therefore obtains for us all graces from God; yet our Lady and the Saints, in virtue of the merits of Jesus Christ, and through the love which unites them with God and with us, help us by their intercession to obtain the graces which we implore, and this is one of the great benefits of the Communion of Saints.
It is also right to honor the sacred images of Jesus Christ and of the Saints, because such honor is referred to their persons. And we also honor the relics of the Saints, because their bodies were living members of Jesus Christ and temples of the Holy Ghost, and will have a glorious resurrection to eternal life.
Between the worship we pay God and that which we pay to the Saints, there is this difference, that we adore God for His infinite perfections, but the Saints, although we do not adore them, we honor and venerate as friends of God and as our intercessors with Him. The worship given to God is called latria or adoration, and that which we give to the Saints is called dulia, i.e., veneration of the servants of God, but the worship which is paid in particular to the Blessed Virgin Mary is called hyperdulia, i.e., special veneration, which we pay to her as the Mother of God.
350. Why is it said at the commencement of the Commandments: I am the Lord thy God?
It is said at the commencement of the Commandments: I am the Lord thy God, to show us that God being our Creator and Lord, can command whatever He wills, and that we, being His creatures, are bound to obey Him.
351. In the words of the First Commandment: Thou shalt not have any other God but Me, what does God command us?
By the words of the First Commandment: Thou shalt not have any other God but Me, He commands us to acknowledge, adore, love and serve Him alone as our Sovereign Lord.
352. How do we fulfill the First Commandment?
We fulfill the First Commandment by the practice of internal and external worship.
353. What is internal worship?
Internal worship is the honor which is given to God with the faculties of the soul alone, that is with the intellect and the will.
354. What is external worship?
External worship is the homage that is given to God by means of outward acts and of sensible objects.
355. Is it not enough internally to adore God with the heart alone?
No, it is not enough internally to adore God with the heart alone. We must also adore Him externally with both soul and body, because He is the Creator and absolute Lord of both.
356. Can there be external worship without internal worship?
No, in no way can there be external worship without internal, because unless external worship is accompanied by internal, it is destitute of life, of merit, and of efficacy, like a body without a soul
357. What is forbidden by the First Commandment?
The First Commandment forbids idolatry, superstition, sacrilege, heresy, and every other sin against religion.
358. What is idolatry?
Idolatry is the giving to any creature - for example, to a statue, to an image, or to a man - the supreme worship of adoration that belongs to God alone.
359. How is this prohibition expressed in Holy Scripture?
This prohibition is expressed in Holy Scripture in these words: "Thou shalt not make to thyself a graven thing, nor the likeness of anything that is in heaven above or in the earth beneath, nor of those things that are in the waters under the earth. Thou shalt not adore them nor serve them."
360. Do these words forbid every kind of image?
Certainly not; but only those of false divinities, made to be adored, as idolaters adore them. So true is this, that God Himself commanded Moses to make images, as, for example, the two statues of the Cherubim for the Ark, and the Brazen Serpent in the desert.
361. What is superstition?
Superstition is any devotion that is contrary to the teaching and practice of the Church; as also the ascribing to any action or any thing whatever a supernatural virtue which it does not possess.
362. What is a sacrilege?
A sacrilege is the profanation of a place, of a person, or of a thing consecrated to God and set apart for his worship.
363. What is heresy?
Heresy is a culpable error of the intellect by which some truth of faith is obstinately denied.
364. What else does the First Commandment forbid?
The First Commandment also forbids all dealings with the devil, and all association with anti-Christian sects.
365. If one were to have recourse to and invoke the devil, would he commit a grave sin?
If one were to have recourse to and invoke the devil, he would commit an enormous sin, because the devil is the most wicked enemy both of God and of man.
366. Is it lawful to put questions to speaking or writing tablets or in any way to consult the souls of the dead by means of Spiritism?
All the practices of Spiritism are unlawful, because they are superstitious; and often they are not free from diabolical intervention; and hence they are rightly condemned by the Church.
367. Does the First Commandment forbid us to honor and invoke the Angels and Saints?
No, it is not forbidden to honor and invoke the Angels and Saints; on the contrary, we should do so, because it is a good and useful practice highly commended by the Church; for they are God's friends and our intercessors with Him.
368. Since Jesus Christ is our only mediator with God, why have recourse also to the intercession of the Blessed Virgin and the Saints?
Jesus Christ is our Mediator with God, because being true God and true man He alone in virtue of His own merits has reconciled us to God and obtains us all graces. But in virtue of the merits of Jesus Christ, and through the charity which unites them to God and us, the Blessed Virgin and the Saints help us by their intercession to obtain the graces we ask. And this is one of the great benefits of the Communion of Saints.
369. May we also honor the sacred images of Jesus Christ and of the Saints?
Yes, because the honor we give the sacred images of Jesus Christ and of the Saints is referred to their very persons.
370. May the relics of the Saints be honored?
Yes, we should honor the relics of the Saints, because their bodies were living members of Jesus Christ and temples of the Holy Ghost, and will rise gloriously to eternal life.
371. What is the difference between the honor we give to God and the honor we give to the Saints?
Between the honor we give to God and the honor we give to the Saints there is this difference, that we adore God because of his infinite excellence, whereas we do not adore the Saints, but honor and venerate them as God's friends and our intercessors with Him. The honor we give to God is called latria, that is, the worship of adoration; the honor we give to the Saints is called dulia, that is, the veneration of the servants of God; while the special honor we give to the Blessed Virgin is called hyperdulia, that is, a special veneration of the Mother of God.