Most people who claim to read, study, and know their Bibles do not know and understand that the Old Testament is a book about Christ and the promise of His coming to establish a righteousness that would enable God to be both a just God and a Savior, a righteousness that would demand the entire salvation of all whom He represented, for whom He lived, died, and rose again (spiritual Israel), a righteousness that would entitle them to all of Heaven. The Old Testament spoke of His incarnation, His perfect obedience, His suffering and death, His burial and resurrection, all based on the fact that He, as the Representative and Surety of God's elect, would satisfy law and justice for them, pay their sin-debt in full, and secure their salvation. Based on the merits of His obedience and death, the Old Testament stated plainly that "ISRAEL SHALL BE SAVED IN THE LORD WITH AN EVERLASTING SALVATION" (Isa. 45:17). "Israel" here is identified in the Old Testament as spiritual Israel, made up of God's elect out of every tribe, kindred, tongue, and nation. It did not refer to Abraham's physical descendants, but Abraham's spiritual descendants. Who are they? They are called "the children of the promise" (Rom. 9:6-8). What does this mean? It means that spiritual Israel is made up of all, Jew and Gentile, who believe a specific promise. What is that promise? It is the promise of the Gospel God's promise to save sinners, freely give them all the benefits and blessings of salvation, and entitle them to all of Heaven based on the righteousness of the Lord Jesus Christ freely imputed and received by faith. All who believe THIS PROMISE are citizens of spiritual Israel. It is said of them "For ye are all the children of God by faith in Christ Jesus. For as many of you as have been baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise" (Galatians 3:26-29).