Updated: Nov 26, 2021
Another excellent reason to read the O.T. is that it greatly helps to connect 21st-century American Christians with their up-to-6000-year-old Jewish roots. In our generation, it's all too easy to forget (or neglect) that we are part of a much bigger story than we generally acknowledge: that God had a purpose and a choosing that goes back to the beginning of recorded history, and even earlier. That it was God who created this world, not mere happenstance; that He created it for His glory, and that He created it for man. That He declared, from the first transgression of the first man, that there would be a Redeemer, the Son of the woman (Genesis 3:15). And He gave hints and clues about that Redeemer all through the pages of the Old Testament text, from the son promised to His chosen man of faith, His friend Abraham ("God will provide for Himself the lamb"—Genesis 22:8), on through to Israel ("in your seed all the families of the earth shall be blessed"—Genesis 28:14), traced through the history of the early judges, prophets, and kings—most notably King David, of whom the Lord said, "David shall never lack a man to sit on the throne of the house of Israel" (Jeremiah 33:17). That same David composed much of the Book of Psalms, many of which notably foresee the life of his greatest Son and his Lord.
The Prophets take up the refrain from there, offering even more clues and hints about the identity of the Messiah, God's Servant, the Son of God. It's worth noting again that up until this point in history, God's chosen people were almost completely Jews—descendants of Abraham, children of Israel. But in the Prophets more of the mystery is uncovered, when God says of the Son, "‘It is too small a thing that You should be My Servant to raise up the tribes of Jacob, and to restore the preserved ones of Israel; I will also give You as a light to the Gentiles, that You should be My salvation to the ends of the earth" (Isaiah 49:6).
Once again, this idea that all the nations of the earth (the Gentiles) have been granted the same favor as God's chosen nation (the Jews) is summarized neatly in the writings of Paul:
Remember that you, once Gentiles in the flesh—who are called Uncircumcision by what is called the Circumcision made in the flesh by hands—that at that time you were without Christ, being aliens from the commonwealth of Israel and strangers from the covenants of promise, having no hope and without God in the world. But now in Christ Jesus you who once were far off have been brought near by the blood of Christ. (Ephesians 2:11-13)
But what is summarized crisply by Paul in the New Testament is written out in elegant longhand in the pages of the Old. It is there in all its agony and its glory: the whole history of God's chosen people (as well as the God who chose them), which things would otherwise be a complete enigma to us Gentiles, were it not for the record of the Old Testament.
I'll wrap up my thoughts about this subject tomorrow (the Lord willing).