Q. 92. What is the law of God?
God spake all these words, Exodus 20, Deuteronomy 5, saying: I am the LORD thy God, which hath brought thee out of the land of Egypt, out of the house of bondage.
Q. 93.How are these commandments divided?
Into two tables; the first of which teaches us how we must behave towards God; the second, what duties we owe to our neighbour.
 Exodus 34:28–29;  Deuteronomy 4:13 and 10:3–4.
Q. 94. What doth God enjoin in the first commandment?
That I, as sincerely as I desire the salvation of my own soul, avoid and flee from all idolatry, sorcery, soothsaying, superstition, invocation of saints, or any other creatures; and learn rightly to know the only true God; trust in Him alone, with humility and patience submit to Him; expect all good things from Him only; love, fear, and glorify Him with my whole heart; so that I renounce and forsake all creatures, rather than commit even the least thing contrary to His will.
 1 Corinthians 6:9–10 and 10:7, 14;  Leviticus 18:21; Deuteronomy 18:10–12;  Matthew 4:10; Revelation 19:10;  John 17:3;  Jeremiah 17:5, 7;  Hebrews 10:36; Colossians 1:11; Romans 5:3–4; Philippians 2:14;  1 Peter 5:5–6;  Psalm 104:27; Isaiah 45:7; James 1:17;  Deuteronomy 6:5; Matthew 22:37;  Deuteronomy 6:5; Matthew 10:28;  Matthew 4:10;  Matthew 5:29–30; Acts 5:29; Matthew 10:37;  Matthew 5:19.
Q. 95. What is idolatry?
Idolatry is, instead of, or besides that one true God, who has manifested Himself in His Word, to contrive, or have any other object, in which men place their trust.
 2 Chronicles 16:12; Philippians 3:18–19; Galatians 4:8; Ephesians 2:12.
The Ten Commandments summarises the Moral Law of God. It is known as the “words of the covenant” (Ex 34:28) and is given very special emphasis by God Himself, when compared to His other commands. All the other laws of God were given by God’s inspiration to Moses and the prophets, but the Ten Commandments alone was spoken audibly by God in the hearing of the people (Ex 20:1, 19; Deut 5:4). All the other laws of God were inscribed using the pens of men, but the Ten Commandments was inscribed with the finger of God on tables of stone—twice (Ex 31:18; 34:1, 28). And again, the Ten Commandments alone, of all the laws of God, was placed in the ark of the covenant by God (Heb 9:4). Moreover, it is very clear that the breaking of these commandments was considered by God to be much more heinous that failure to worship Him with burnt offerings and sacrifices (cf. Jer 7:22–23; Jer 11:2–4; Ex 19:5–6; 1 Sam 15:22).
It is clear that the Ten Commandments can be divided into two parts, with the first four commandments dealing with our duty to love God with our whole being, and the second six commandments dealing with our duty to love our neighbour as ourselves. While the second table is quoted in the New Testament (e.g., Mt 19:18–19; Rom 13:9), the commandments in the first table are not quoted directly anywhere in the New Testament. The most likely reason for this is that the first table, which deals with our duty to love God, is so sacred and fundamental that it is sacrilegious for the Jews and early believers not to know them or strive to obey them.
Q/A 94–95 deals with the First Commandment. It is interesting to note that most people today will think of idolatry being forbidden in the Second Commandment rather than the First, but I believe the Reformed creeds are correct: Idolatry has to do with the worship of or the giving of honour to other gods, whether they are cast in iron or wood or otherwise, therefore idolatry is the breaking of the First Commandment. The Second Commandment, on the other hand, has to do with the worship of Jehovah with the use of images.
Of course, the First Commandment is also broken when we give the honour and priority due to God to anything, even if we may not consider them to be gods. Thus, if my life revolves around my career, then my career has become my idol. In the same way, if I do not believe in the existence of God, but believe only in myself, then I have become my idol. I am then guilty of I-dolatry.
Heidelberg Catechism >