Some time ago, in his "A Moment of Hope" radio commentary, a local preacher spoke of the power of words and how, if we want our lives to be hopeful, we need to keep our speech positive. He then quoted Proverbs 18:21 as wisdom on the subject: "Death and life are in the power of the tongue, and those who love it will eat its fruit."
So far, everything was fine—and then he went and spoiled it by saying (paraphrasing), "You can find that in the Jewish Testament of your Bible."
The Jewish Testament? What is that? There is no such thing! We could call the Old Testament "the Hebrew Testament" with some legitimacy because it was written in Hebrew, but what would make it Jewish? Was he trying to say that, if we read only the Old Testament, we would become followers of Judaism? Or, that the Jews somehow own the Old Testament? Or, that because the Old Testament is revered by Jews as their holy book, it is somehow inferior to "the Christian Testament?"
Certainly, the Bible never calls the Old Testament "the Jewish Testament." Paul calls it "the Holy Scriptures" in II Timothy 3:15. Jesus calls it "the Law of Moses and the Prophets and the Psalms" in Luke 24:44. In many places, the writers simply refer to it as "the word [of God or of the Lord]" or "the Scripture(s)." The only hint that the Old Testament "belongs" to the Jews is a misinterpretation of Romans 3:2, "to them were committed the oracles of God." This means only that the Jews are responsible for their accurate transmission throughout history, not that they apply only to Jews or that Jews exclusively possess them in some way.
No, this all stems from the mistaken idea that the Old Testament is the Old Covenant, "becoming obsolete and growing old . . . ready to vanish away" (Hebrews 8:13), while the New Testament is the New Covenant. Thus, to a "Christian" under the New Covenant, anything that appears in the Old Testament is of lesser value than what appears in the New Testament. This error has led to countless misunderstandings and misinterpretations of the message Jesus brought to mankind.
In fact, the New Testament cannot be understood without the foundation of the Old Testament—and not just in historical terms. Paul is not overstating things when he says the church is "built on the foundation of the apostles and prophets, Jesus Christ being the chief cornerstone" (Ephesians 2:20). After His resurrection, Jesus "beginning at Moses and all the Prophets, . . . expounded to [the disciples] in all the Scriptures the things concerning Himself" (Luke 24:27). Later, "He opened their understanding, that they might comprehend the Scriptures" (verse 45). Which Scriptures? The Old Testament, of course, the only ones written at the time!
Just these few verses say that we New Covenant Christians cannot understand Jesus Christ, His doctrine, His church, and God's plan without the Old Testament. We can see this by how frequently the apostles quote from the writings of Moses, David, and the prophets to support and fill out their doctrinal teachings. There is hardly a page in the New Testament that does not have a quotation or allusion to the Old Testament on it. It is a vital part of New Covenant—New Testament—Christianity!
Lack of space does not permit an explanation of the differences between the Old Covenant and the New. However, let it suffice to say that the major problem in the Old Covenant was the people with whom God made it (see Hebrews 8:7-12; Romans 8:3). The New Covenant is modeled after the Old with its basic law, the Ten Commandments, retained in all its force and wisdom. In fact, Jesus makes it plain that He added intent to the law's scope so that it is now stricter under the New Covenant (Matthew 5:17-48)!
In the end, we must conclude that the Bible is a whole with two parts, which came as a result of the ministry of Jesus Christ and the languages in which the two parts were penned. The theology and the goal of the instruction in the two are the same. The same God who never changes rules, acts, and speaks in both. Those who believed and lived by faith in both eras will receive the same gift of eternal life (I Thessalonians 4:14-17; Hebrews 11:40).
Please be aware of this false notion of the Old Testament's inferiority to the New, as it colors a great deal of "Christian" biblical commentary. The Word of God is God's Word, whether spoken in 1400 BC or AD 60. Above all, remember our Savior's instruction, quoting from Deuteronomy 8:3, "Man shall not live by bread alone, but by every word that proceeds from the mouth of God" (Matthew 4:4).