Question: "What is Covenant Theology and is it Biblical?"
Answer: Covenant theology is based on the theory that God has only one covenant with men (the covenant of grace) and only one people, represented by the Old and New Testament saints—one people, one church and one plan for all. These beliefs require the adherents of Covenant Theology to interpret prophecy in a nonliteral way. Dispensationalism, on the other hand, is a system of theology with two primary distinctives: (1) a consistently literal interpretation of Scripture, especially Bible prophecy, and (2) a distinction between Israel and the Church in God's program.
Those who hold to Covenant Theology believe that there is, and has always been, only one people of God. They believe that Israel was the Church in the Old Testament, and the Church is Israel in the New Testament. The promises of land, many descendants, and blessing to Israel in the Old Testament have been “spiritualized” and applied to the Church in the New Testament because of Israel’s unbelief and rejection of their Messiah. Those who hold to Covenant Theology also do not interpret prophecy in a normal sense. As an example, in Revelation 20, the thousand year reign of Christ is spoken of. Covenant Theology would say that the number 1,000 is symbolic and really does not mean a literal 1,000 years. They would say that we are in the millennium right now, that the reign of Christ with his saints is going on in heaven right now, and that the 1,000 year period is symbolic, beginning with the first coming of Christ and ending when He returns.
Scripturally, Covenant Theology is wrong in both how Israel is viewed and how prophecy is interpreted. The proper method for interpreting Scripture is to read it in a normal sense. Unless the text indicates that it is using some kind of figurative language, it should be taken literally. When Scripture speaks of Israel, it is not referring to the Church, and when the Church is spoken of, it is not referring to Israel. God has one plan for Israel and another for the Church. Also, with reference to prophecy, all prophecies that have been fulfilled were fulfilled literally, not figuratively. Christ literally fulfilled the Old Testament prophecies about the Messiah when He came 2,000 years ago. There is no reason to think that unfulfilled prophecies are to be understood in a figurative sense. As with those in the past, future prophecy will be fulfilled literally in the future.
In Romans 11:1, Paul poses the question of Israel’s future and answers it definitively: “I ask then: ‘Did God reject his people?’ By no means!” The rest of the chapter makes it clear that Israel has been “hardened” or temporarily set aside “in part until the full number of the Gentiles has come in” (Romans 11:25). Israel did not become the Church; rather, the Church was “grafted in” (v. 17) to the root of God’s family, creating one body out of the two, while they remain separate in origin, although united in the faith. If the Church was to replace Israel, the imagery would be as a tree (Israel) uprooted and replaced by another (the Church). But the imagery of a branch grafted into a tree is perfectly clear. This is the “mystery” Paul speaks of in verse 25. A mystery in the New Testament refers to something previously not revealed, and the idea of another group of people becoming part of the chosen people of God was unheard of to the Jews at that time.
Will God cast away His people Israel? No, God will not cast away His people. On the contrary, verse 25 and following says, "God will save his people." At some future point, “the deliverer will come from Zion; he will turn godlessness away from Jacob.” Here is God’s promise to His chosen people for their future restoration. What a glorious plan! No wonder the contemplation of it caused Paul to burst forth with “Oh, the depth of the riches of the wisdom and knowledge of God! How unsearchable his judgments, and his paths beyond tracing out!” God is faithful, He is merciful and His plans are perfect, and one day both Jew and Gentile will worship the Lord Jesus Christ as one body.