In the foreword to Dr. J. Alec Motyer‘s excellent little book, A Christian’s Pocket Guide to Loving the Old Testament, Tim Keller shares this fantastic insight he learned from the good doctor a few decades ago.

Approximately 40 years ago, during the summer between my undergraduate college years and seminary, I  . . . came eventually to the Ligonier Valley Study Center . . . where R. C. Sproul was hosting at his regular weekly Question and Answer session a British Old Testament scholar, J. Alec Motyer. As a still fairly new Christian, I found the Old Testament to be a confusing and off-putting part of the Bible.

I will always remember his answer to a question about the relationship of Old Testament Israel to the church . . . After saying something about the discontinuities, he insisted that we were all one people of God. Then he asked us to imagine how the Israelites under Moses would have given their “testimony” to someone who asked for it. They would have said something like this:

We were in a foreign land, in bondage, under the sentence of death. But our mediator—the one who stands between us and God—came to us with the promise of deliverance. We trusted in the promises of God, took shelter under the blood of the lamb, and he led us out. Now we are on the way to the Promised Land. We are not there yet, of course, but we have the law to guide us, and through blood sacrifice we also have his presence in our midst. So he will stay with us until we get to our true country, our everlasting home.

Then Dr. Motyer concluded:

“Now think about it. A Christian today could say the same thing, almost word for word.”

My young self was thunderstruck. I had held the vague, unexamined impression that in the Old Testament people were saved through obeying a host of detailed laws but that today we were freely forgiven and accepted by faith. This little thought experiment showed me, in a stroke, not only that the Israelites had been saved by grace and that God’s salvation had been by costly atonement and grace all along, but also that the pursuit of holiness, pilgrimage, obedience, and deep community should characterize Christians as well.

Taken from “A Christian’s Pocket Guide to Loving the Old Testament, p. ix-x)

What is concealed in the Old Testament is revealed in the New Testament and what is revealed in the New is concealed in the Old. As the author of Hebrews put it, “The law has but a shadow of the good things to come” (Hebrews 10:1). As Jesus put it, “You search the Scriptures because you think that in them you have eternal life; and it is they that bear witness about me” (John 5:39).