The unity of God's plan

Vern S. Poythress, in his contribution to Understanding the Big Picture of the Bible entitled An Overview of the Bible's Storyline, writes,

The work of Christ on earth, and especially his crucifixion and resurrection, is the climax of history; it is the great turning point at which God actually accomplished the salvation toward which history had been moving throughout the Old Testament. The present era looks back on Christ's completed work but also looks forward to the consummation of his work when Christ will come again and when there will appear "new heavens and new earth in which righteousness dwells" (2 Pet. 3:13; see Rev. 21:1-22:5).

The unity of God's plan makes it appropriate for him to include promises and predictions at earlier points in time, and then for the fulfillments of these to come at later points. Sometimes the promises take explicit form, as when God promises the coming of the Messiah, the great Savior whom Israel expected (Isa. 9:6-7). Sometimes the promises take symbolic form, as when God commanded animal sacrifices to be offered as a symbol for the forgiveness of sins (Leviticus 4). In themselves, the animal sacrifices were not able to remove sins permanently and to atone for them permanently (Heb. 10:1-18). They pointed forward to Christ, who is the final and complete sacrifice for sins. (8)