|(Baptism! With Ferris State students in west Michigan.)|
Imagine there was a play, about which you knew nothing.
This imaginary play has five acts.
You go to see the play enacted, but arrive late. You miss the first three acts. As you watch Act 4, you understand little. Or, you misunderstand and misinterpret what is happening.
It's the same with the Bible. If you jump into the four Gospels without an understand of the first three acts (the Old Testament: creation, evil enters the world, God calls out a people for his purposes), you will misinterpret the Jesus story.
This is N.T. Wright's thesis. In an interview, Wright says:
"If one doesn’t know the Old Testament, one doesn’t have a chance of understanding the New, because again and again, and you see this in the Gospels, the way they told a story is not just with the odd glance over their shoulder – that something interesting happened back there and this is an odd reference. Like I might drop a reference to a Shakespeare play into a speech or a book I was writing or something that is just for decoration. Some people think the Old Testament is just a back decoration. It’s much, much more than that."
(In Trinitarian Conversations Volume 2: Interviews With More Theologians. Emphasis mine.)