When one studies the Scriptures, it becomes apparent there is a profound unity between the Old and New Testaments. For example, this unity is demonstrated by the fact that over one third of the New Testament is made up of quotes from the Old Testament. In truth, many Old Testament passages simply could not be understood without the New Testament. Consider the numerous prophecies referring to Jesus Christ, such as those in Psalm 22 and Isaiah 53. Without the writings of the New Testament, we would never realize that such texts were Messianic in nature.
Similarly, dozens of Old and New Testament prophecies regarding the end time could not be understood without the book of Revelation. And, without a thorough knowledge of the Sabbath and holy days—which are fully explained only by referencing both the Old and New Testaments—the general prophetic time frame for the fulfillment of the plan of God cannot be understood.
These examples demonstrate the unity of Scripture, and are proof of God’s inspiration of the entire Bible as the complete Word of God. In the book of Isaiah, God provides us with the standard by which to seek Him and understand His Word, as well as to discern those who speak the truth: “To the law and to the testimony! If they do not speak according to this Word, it is because there is no light in them” (Isa. 8:20). In this same chapter we also find a prophecy showing that the New Testament would be written by Jesus’ disciples, or apostles: “Bind up the testimony, seal the law among My disciples” (verse 16). Because this verse foretells of the New Testament, it is also a prophecy that the Old Testament alone would not comprise the complete Word of God.
Indeed, the apostle Paul wrote to the Colossians that he was to help “complete the Word of God” with his epistles (Col. 1:25). Paul also wrote to Timothy concerning the Old Testament: “But as for you, continue in the things that you did learn and were assured of, knowing from whom you have learned them; and that from a child you have known the holy writings [the Old Testament], which are able to make you wise unto salvation through faith, which is in Christ Jesus” (II Tim. 3:14-15). Paul is showing that salvation involves not only faith in Christ and New Testament teachings, but that Old Testament teachings are necessary as well. Paul then shows that all Scripture—Old and New Testament—is inspired by God: “All Scripture is God-breathed and is profitable for doctrine, for conviction, for correction, for instruction in righteousness; so that the man of God may be complete, fully equipped for every good work” (verses 16-17).
Unity Through the Laws and Commandments of God
The unity between the Old and New Testaments is perhaps most obvious in the fact that the New Testament fully upholds the laws and commandments of God. Jesus demonstrated this when He answered the Devil’s temptation by quoting Deuteronomy 8:3: “It is written, ‘Man shall not live by bread alone, but by every word that proceeds out of the mouth of God’ ” (Matt. 4:4). This includes the entire Word of God—the Old Testament and whatever Christ would speak and have recorded in the New Testament—because Jesus was God manifested in the flesh.
In the Sermon on the Mount, Jesus made it absolutely clear that He did not come to do away with the Law and the Prophets: “Do not think that I have come to abolish the Law or the Prophets; I did not come to abolish, but to fulfill. For truly I say to you, until the heaven and the earth shall pass away, one jot or one tittle shall in no way pass from the Law until everything has been fulfilled” (Matt. 5:17-18). Jesus went on to say: “Therefore, whoever shall break one of these least [Old Testament] commandments, and shall teach men so, shall be called least in the kingdom of heaven; but whoever shall practice and teach them, this one shall be called great in the kingdom of heaven” (Matt. 5:19).
When a scribe asked Jesus which was the greatest commandment of the Law, He gave no indication whatsoever that any of God’s laws were obsolete. Rather, Christ responded by quoting Deuteronomy 6:4-5, thus welding together the Old and New Testaments—making them one: “And one of them, a doctor of the law, questioned Him, tempting Him, and saying, ‘Master, which commandment is the great commandment in the Law?’ And Jesus said to him, ‘You shall love the Lord your God with all your heart, and with all your soul, and with all your mind. This is the first and greatest commandment; and the second one is like it: ‘You shall love your neighbor as yourself’ ” (Matt. 22:35-39). Jesus was saying that one cannot express complete love toward God and neighbor without the commandments of God. As if to erase all doubt, He then said, “On these two commandments hang all the Law and the Prophets” (verse 40).
In concert with Jesus’ statements, numerous Old Testament passages show that Christ—as the God of the Old Testament—would never abolish or do away with His own commandments. “The works of His hands are truth and judgment; all His commandments are sure. They stand fast forever and ever…” (Psa. 111:7-8). Through the prophet Isaiah, God proclaims that His “righteousness [which is defined by His law] shall not be abolished” (Isa. 51:6). Thus, His Law stands forever.
Other passages demonstrating the unity of Scripture can be found in Psalm 119—where nearly every verse declares the greatness and truth of God’s Word and confirms what Jesus said. Here are a few examples: “Your law is the truth” (verse 142); “You are near, O LORD , and all Your commandments are truth” (verse 151); “Your word is true from the beginning; and every one of Your righteous judgments endures forever” (verse 160); and, “Therefore I love Your commandments above gold—yea, above fine gold. Therefore I esteem all Your precepts concerning all things to be right, and I hate every false way” (verses 127-128).
The entirety of Psalm 119 can also be considered a prophecy of Jesus’ innermost thoughts concerning the laws, commandments, statutes, testimonies, judgments and precepts of God. Jesus Christ—Who was God manifested in the flesh and the living Word of God—told His apostles, “I am the way, and the truth and the life; no one comes to the Father except through Me” (John 14:6). “The Way” means that the only way to fully live for God is through Jesus. “The Truth” means that Jesus was the personification of God’s truth—the entire Word of God—and that He did not come to abolish any of God’s laws. “The Life” means that eternal life—as a gift from the Father—comes only through the life, death and resurrection of Jesus.
Again showing the unity between the Old and New Testaments, the apostle John made this straightforward statement: “By this standard we know that we love the children of God: when we love God and keep His commandments. For this is the love of God: that we keep His commandments; and His commandments are not burdensome” (I John 5:2-3).
Indeed, the Scriptures are deeply integrated—demonstrating that the Old and New Testaments together truly make up the complete, unified Word of God.