The Bible is one book with one major message written over a period of 1600 years. The unity of the Bible is one of its marvels. The patriarch Abraham is a prime example. God gave Abraham a tremendous promise. "In you all the families of the earth will be blessed" (Genesis 12:3). The Bible says, "Then he believed in the Lord; and He reckoned it to him as righteousness" (Genesis 15:6). We read this in the very first book of the Old Testament of the Bible.
Abraham becomes a model for New Testament believers. The apostle Paul teaches, "The Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying ‘All the nations will be blessed in you’" (Galatians 3:8). The ancient promise God gave Abraham is the gospel. God fulfilled this gospel promise by sending Christ into the world.
Those who believe the promise of God regarding Christ follow the example of Abraham. As Paul again says, "So then those who are of faith are blessed with Abraham, the believer" (Galatians 3:9). Not only so, "If you belong to Christ, then you are Abraham’s descendants, heirs according to promise" (Galatians 3:29).
The gospel of Christ binds the Bible together. If you catch this theme, you see the Bible’s unity. The Bible steps out of history into your heart.