How is the Bible a unity? The Scriptures makes it clear that God has a unified plan for all of history. God’s ultimate purpose realized in the fullness of time is to unite all things in Christ (Ephesians 1:10). The Old Testament contains God’s promises and covenants. All of these were shadows, prefigurements, and types.
The article traces the meaning of the phrase "the fullness of time," which relates to the various times in which God fulfilled his promises and will fulfill remaining promises to his people.