1. The Center of the Old Testament: The Ten Commandments at Sinai
The Christian Bible is clearly divided into the “Old Testament” and the “New Testament.” Understanding the boundary and essence of these two is key to grasping the core of the Christian faith. Paul testifies that the Old Testament is the Ten Commandments given at Mount Sinai (Galatians 4:24). In other words, the starting point and center of the Old Testament is the commandments of God received at Sinai—the Ten Commandments (Exodus 19:20).

2. The Ten Commandments, the Temple, and the Structure of Sacrifice
The Ten Commandments were not just moral rules, but the foundation for the faith and life of God’s people. To keep these commandments, Israel made the Ark of the Covenant and built the Tabernacle (and later, the Temple) (Exodus 25:16; 40:20–21). The Temple was the place of God’s presence and meeting (Exodus 25:22). However, approaching the holy God required rituals for the forgiveness of sins (Leviticus 16). Thus, the Old Testament established various feasts and sacrifices—Sabbath, Passover, Unleavened Bread, Firstfruits, Weeks/Pentecost, Trumpets, Day of Atonement (Leviticus 16:29–32), etc. These were spiritual pathways to stand before God. The Most Holy Place (Leviticus 16:2; Hebrews 9:7), which only the high priest could enter once a year on the Day of Atonement, was the climax of all feasts and sacrifices.

3. The Law, Purity Codes, and Human Limitations
Another barrier for the people seeking to approach the Temple according to the law was ritual impurity—unclean foods (Leviticus 11), contact with corpses (Numbers 19:11–13), and many other purity laws had to be observed. These were essential requirements for approaching God and are detailed throughout the Torah from Genesis to Deuteronomy.

4. The Heart of the Ten Commandments: Love for God and Neighbor
The Ten Commandments can be divided into two parts: the first four are commandments to love God (Exodus 20:1–11), and the remaining six are to love one’s neighbor (Exodus 20:12–17). Jesus summarized the essence of the Ten Commandments as: “Love the Lord your God with all your heart, soul, and mind… and love your neighbor as yourself” (Deuteronomy 6:5, Leviticus 19:18, Matthew 22:37–40). Especially, the commandments about loving God were concretely practiced through Temple worship, sacrifices, and feasts (Sabbath, Passover, Day of Atonement, etc.).

5. The Limitations of the Commandments and the Prophets’ Appeals
Yet these commandments were engraved on tablets of stone or written texts (Exodus 31:18; Deuteronomy 9:10), so the people often forgot them, failing to make them a habit, and thus repeatedly sinned (Romans 7:7–25). As a result, God sent many prophets to call for repentance and command obedience (Isaiah 1:16–17, Jeremiah 7:23–26, Micah 6:6–8), but the Israelites still did not obey, leading to the tragedy of their nation’s destruction by Babylon (2 Chronicles 36:15–17, Jeremiah 25:8–11).

6. The Beginning of the New Covenant Written on the Heart
Because these commandments were inscribed on tablets or written texts, the people frequently forgot them and kept repeating sin (Romans 7:7–25). God sent many prophets urging repentance and commandment-keeping (Isaiah 1:16–17, Jeremiah 7:23–26, Micah 6:6–8), but Israel did not obey and was ultimately destroyed by Babylon (2 Chronicles 36:15–17, Jeremiah 25:8–11).

7. The Fulfillment of the Law through Jesus Christ
Jesus fulfilled every prophecy in the order of the law. His death on the cross was the completion of the earthly sacrificial system (Hebrews 9:11–14). His resurrection and ascension fulfilled the prophecy of the high priest entering the Most Holy Place (Hebrews 9:2–4; 10:1–2). The expulsion of Satan from heaven corresponds to the scapegoat ritual on the Day of Atonement (Leviticus 16:21–22, Revelation 12:7–10). The coming of the Holy Spirit fulfills the prophecy of Tabernacles—now, each believer is a living temple and Most Holy Place of God (John 7:37–39, 1 Corinthians 3:16–17, Ephesians 2:21–22).

8. The New Testament: The Holy Spirit and the New Most Holy Place
Therefore, those who have received the Holy Spirit through Jesus have already entered the Most Holy Place (Hebrews 10:19–22). The Spirit enables believers to understand the deep things of God (1 Corinthians 2:10–12), and New Testament believers are no longer bound to ritual observances such as the Sabbath or Day of Atonement—they are people of the New Covenant (Colossians 2:16–17, Hebrews 10:18).

9. Conclusion: Old Testament—The Ten Commandments; New Testament—The Holy Spirit
The Bible shows the progressive path of humanity’s salvation in the flow of the Old and New Testaments. The Old Testament was the age of the Ten Commandments given at Sinai, the law written on stone. But the law could not fundamentally transform the human heart, leading to repeated sin and human limitations. Therefore, God opened a new era of redemption through Jesus Christ. The Holy Spirit sent by Jesus now writes the commandments not on tablets or paper, but on the hearts of believers (Romans 8:2, 2 Corinthians 3:3, Hebrews 8:10–13). Those who receive the Spirit become the true temple where God dwells, and God’s will and love are written in their hearts as people of the New Covenant. Thus, the Bible proclaims the era of the Spirit from heaven—commandments written on the heart and eternal union with God, going beyond the limits of the law.