Questions 102-106 of the Westminster Larger Catechism (WLC) set forth in greater detail the meaning of the 1st Commandment. Here they are set out so that they can be read responsively in worship.
Question 102: What is the sum of the four commandments which contain our duty to God?
Answer: The sum of the four commandments containing our duty to God is, to love the Lord our God with all our heart, and with all our soul, and with all our strength, and with all our mind.
Question 103: Which is the first commandment?
Answer: The first commandment is, Thou shall have no other gods before me.
Question 104: What are the duties required in the first commandment?
Answer: The duties required in the first commandment are, the knowing and acknowledging of God to be the only true God, and our God;
and to worship and glorify him accordingly, by thinking, meditating, remembering, highly esteeming, honoring, adoring, choosing, loving, desiring, fearing of him;
believing him; trusting, hoping, delighting, rejoicing in him; being zealous for him;
calling upon him, giving all praise and thanks, and yielding all obedience and submission to him with the whole man;
being careful in all things to please him, and sorrowful when in anything he is offended; and walking humbly with him.
Question 105: What are the sins forbidden in the first commandment?
Answer: The sins forbidden in the first commandment are, atheism, in denying or not having a God;
idolatry, in having or worshiping more gods than one, or any with or instead of the true God; the not having and avouching him for God, and our God;
the omission or neglect of anything due to him, required in this commandment;
ignorance, forgetfulness, misapprehensions, false opinions, unworthy and wicked thoughts of him;
bold and curious searching into his secrets; all profaneness, hatred of God;
self-love, self-seeking, and all other inordinate and immoderate setting of our mind, will, or affections upon other things, and taking them off from him in whole or in part;
vain credulity, unbelief, heresy, misbelief, distrust, despair, incorrigibleness, and insensibleness under judgments, hardness of heart, pride, presumption, carnal security, tempting of God;
using unlawful means, and trusting in lawful means; carnal delights and joys;
corrupt, blind, and indiscreet zeal; lukewarmness, and deadness in the things of God; estranging ourselves, and apostatizing from God;
praying, or giving any religious worship, to saints, angels, or any other creatures; all compacts and consulting with the devil, and hearkening to his suggestions;
making men the lords of our faith and conscience; slighting and despising God and his commands;
resisting and grieving of his Spirit, discontent and impatience at his dispensations, charging him foolishly for the evils he inflicts on us;
and ascribing the praise of any good we either are, have, or can do, to fortune, idols, ourselves, or any other creature.
Question 106: What are we specially taught by these words “before me” in the first commandment?
Answer: These words “before me,” or before my face, in the first commandment, teach us, that God, who sees all things, takes special notice of, and is much displeased with, the sin of having any other God: that so it may be an argument to dissuade from it, and to aggravate it as a most impudent provocation: as also to persuade us to do as in his sight, whatever we do in his service.