Here's a bit more of his argument in a recent Christianity Today interview:
The old theologians used to speak of "the love for Scripture" as a sign of true faith in Christ. They would say, "We should read the Old Testament as if it were written with the blood of Christ." For them, the Old Testament and the Pentateuch in particular was a Christian book, a book about Christ. For most evangelical Christians today it is a book about archaeology and ancient history.What all this means is that the Pentateuch isn't primarily a record of Israel's religion. It's not primarily about how we should live. It's not a history of important things that happened before Jesus (though the things it says happened, did). It's about Jesus. And I especially appreciate his caution against finding Jesus in every nook and cranny of the OT. Just as George Washington won't appear as a character on every page of a book about him, so Christ doesn't appear on every page, even though every page contributes in some way to the message about Christ that the whole book communicates.
Here we have to be careful because, to be sure, the Old Testament is about ancient history. But that is not its meaning. Its meaning is Christ. Saying that also calls for a great deal of caution. In my book, I take the view that the whole of the Pentateuch is about Christ, but that doesn't mean that Christ is in the whole Pentateuch. Finding Christ in the Pentateuch means learning to see him when he is there rather than trying to see when he is not there. I like to tell my students that we don't need to spiritualize the Old Testament to find Christ, but we do need to read it with spiritual eyes.
Now having said all that, I'm not recommending that you go out and buy Sailhamer's new book unless you're pretty serious about digging into the issues. It's really long and fairly technical, though quite readable in the early-going. Instead, I'd encourage you to start with his NIV Compact Bible Commentary. It's an excellent, efficient tool to help you pick up on the major themes of Scripture, particularly the narrative passages and the prophets. And the "NIV" in the title is simply a publisher's marketing strategy; it's irrelevant to the content.