Reading the Ten Commandments: Preface, Substance, and Reasons

In our last devotional, we considered the rules that help us understand the Ten Commandments rightly. Those rules remind us that God’s law is perfect, spiritual, and searching. It addresses not only outward actions but also the heart. Westminster Larger Catechism Question 100 now helps us see how we should approach the commandments themselves: “What specific things are we to consider in the Ten Commandments?” “We are to consider in the Ten Commandments the preface, the substance of the commandments themselves, and the various reasons added to some of them to reinforce them.”

The Ten Commandments are not a random collection of moral instructions. They come from the covenant God who has redeemed a people for Himself. When we read them, we should consider their opening words, their actual commands, and the reasons God graciously gives for obeying them. Each part teaches us something about God, our duty, our sin, and our need for Christ.

Reading the Ten Commandments Through the Preface

Before giving the first commandment, God says, “I am the LORD your God, who brought you out of the land of Egypt, out of the house of slavery” (Exodus 20:2). This is the preface to the Ten Commandments, and it is important.

God does not begin by merely announcing His authority, though He certainly has all authority as Creator. He identifies Himself by His covenant name, “the LORD,” and reminds Israel of His redeeming work. He is the God who delivered them from slavery. It is a statement that the law comes from the Redeemer.

That order is important. Israel was not redeemed because it had first kept God’s law. The Lord rescued His people by grace and then instructed them how to live as His people. In the same way, Christians are not saved by obedience to God’s commands. We are saved by grace alone through faith in Christ alone (Ephesians 2:8–9). Yet those whom Christ saves are also called to walk in the good works God has prepared for them (Ephesians 2:10).

The preface to the Ten Commandments therefore gives both comfort and motivation. The God who commands us is not cruel or distant. He is the faithful God who rescues His people. Christ has delivered His people from the greater bondage of sin and death. Because He is our Savior and Lord, we should desire to obey Him.

When obedience feels difficult, remember who speaks in the Ten Commandments. The voice of God’s law is the voice of the God who says, “I am the LORD your God.” His commands are not meant to drive His redeemed people away from Him, but to teach them the good and faithful way of life with Him.

Reading the Ten Commandments in Their Substance

We must also consider the substance of the Ten Commandments themselves. God tells us what He requires. The first four commandments direct us chiefly to our duty toward God: worshiping Him alone, refusing idolatry, honoring His name, and remembering His Sabbath. The last six commandments direct us chiefly to our duty toward others: honoring authorities, preserving life, pursuing purity, speaking truth, respecting what belongs to others, and being content.

Jesus summarized this substance when He taught that the greatest commandment is to love the Lord our God with all our heart, soul, and mind, and that the second is like it: “You shall love your neighbor as yourself” (Matthew 22:37–39). He added, “On these two commandments depend all the Law and the Prophets” (v. 40).

This does not make the Ten Commandments less important. Rather, it shows their unity. Every commandment teaches us how love for God or love for neighbor should be expressed. We love God by giving Him the worship, reverence, and devotion that belong to Him alone. We love our neighbor by seeking his good in our words, actions, and even our desires.

The substance of the Ten Commandments also reveals how deeply sin reaches into us. We may be tempted to look at the commandments only outwardly: I have not murdered, stolen, or committed adultery. But Jesus shows that hatred violates the sixth commandment and lust violates the seventh (Matthew 5:21–22, 27–28). The tenth commandment reaches directly into the heart by forbidding coveting.

The law exposes us. It shows that we have not loved God as we should or loved our neighbor as ourselves. It leaves us unable to claim righteousness before God. But this is one of the law’s great mercies: it leads us to Christ. He alone loved the Father perfectly and loved His neighbor completely. He bore the curse deserved by lawbreakers so that all who trust in Him may be forgiven and counted righteous before God (Galatians 3:13).

Reading the Ten Commandments With Their Reasons

The catechism also directs us to consider the reasons added to some of the Ten Commandments. God does not need to explain Himself to us. His authority alone is enough. Yet in His kindness, He often gives reasons that reinforce His commands and help us understand their seriousness.

Consider the second commandment. God warns against idolatry because He is “a jealous God” (Exodus 20:5). His jealousy is not sinful insecurity. It is the holy zeal of a husband for the exclusive love of his bride. Since God alone is God, He alone deserves our worship.

The fifth commandment promises blessing: “Honor your father and your mother, that your days may be long in the land” (Exodus 20:12). It teaches that God delights in ordered homes, respect for rightful authority, and a society shaped by His wisdom.

The fourth commandment calls us to remember the Sabbath because God Himself rested after His work of creation (Exodus 20:8–11). The command teaches us that we are creatures, not self-sufficient machines. We need regular rest, worship, and a renewed remembrance that God, not our constant labor, sustains us.

These reasons should make us pause when reading the Ten Commandments. God’s commands are never arbitrary. They reflect His own holy character and promote the good of those who obey Him. His warnings are serious because sin is serious. His promises are precious because He is a gracious Father.

Reading the Ten Commandments in the Light of Christ

The Ten Commandments should humble us, instruct us, and ultimately lead us to Christ. We do not read them as a ladder by which we climb into God’s favor. Christ has secured that favor for His people through His perfect obedience and atoning death.

But neither do we set the commandments aside. The redeemed heart learns to say with the psalmist, “Oh how I love your law!” (Psalm 119:97). God’s law no longer stands over us as a sentence of condemnation, for “there is therefore now no condemnation for those who are in Christ Jesus” (Romans 8:1). It now serves as a loving guide for those who belong to Him.

As you read the Ten Commandments, consider the preface: the Lord is your Redeemer. Consider the substance: He calls you to love Him and your neighbor. Consider the reasons: His commands flow from His wisdom, holiness, and goodness. And then look to Christ, who has fulfilled the law for His people and is faithfully shaping them into willing, joyful servants of God.

Soli Deo Gloria