KEY THOT: Cleopas and the other disciple were leaving Jerusalem and on the way to Emmaus when Jesus appeared to them. They were obviously very sad as they thought that their hope concerning Jesus of Nazareth as the promised Christ was dashed. Then Jesus opened the OT Scripture, "beginning with Moses and all the Prophets, he interpreted to them in all the Scriptures the things concerning himself" ( Luke 24:27). In other words, the Gospel of Christ was already proclaimed in the OT Scriptures. As it has been said: the OT is Christ concealed and the NT is Christ revealed.
Martin Luther calls this the "Law and Gospel" interpretation of the Scripture: not just that the Law serves only to point us to Christ but that the Gospel itself is embedded and taught in the Law and Prophets. In Luke 24:44, Jesus even included the Psalms as Scriptures speaking about Him: "These are my words that I spoke to you while I was still with you, that everything written about me in the Law of Moses and the Prophets and the Psalms must be fulfilled" (Luke 24:44). This is three-fold division of the Hebrew Bible: Law, Prophets and Psalms. In other word, the Gospel is found not just in isolated "messianic" passages scattered here and there, but in its entirety.
While the "Law and Gospel" hermeneutical principle is very helpful in interpreting the Scripture (theologians call it the Christological or Christcentric approach to the OT), it is can result in rejecting certain OT and NT books that do not quite fit this "Law and Gospel" understanding. In order to fully embrace every book of the OT as "Gospel" we need to use a broader hermeneutical approach of the Gospel of the Kingdom of God. Jesus' Gospel is about the Kingdom of God: "The time is fulfilled, and the kingdom of God is at hand; repent and believe in the gospel."
If we understand the Gospel as about God's rule on earth, then the entire OT becomes a relevant to us, beginning from Genesis 1:1, "In the beginning, God created the heavens and the earth. The earth was without form and void, and darkness was over the face of the deep. And the Spirit of God was hovering over the face of the waters" (Genesis 1:1-2). The Gospel of Kingdom is rooted in the Creation of the heavens and the earth, over which God is the King who has the sovereign right to rule over it: this is the Gospel of the Kingdom. When we submit to this rule, we are subject to Christ who has been appointed as the Messiah-King.
With this understanding of the Gospel as about God's rule, Israel was not just a negative demo for NT believers but a positive example of a people under God's rule. Even Christ was with them in the wilderness: "I want you to know, brothers, that our fathers were all under the cloud, and all passed through the sea, and all were baptized into Moses in the cloud and in the sea, and all ate the same spiritual food, and all drank the same spiritual drink. For they drank from the spiritual Rock that followed them, and the Rock was Christ" (1 Corinthians 10:1-4). So, the entire history of Israel is a story about Christ saving and sanctifying the people. However, Paul uses that to warn NT believers that despite having Christ, "with most of them God was not pleased, for they were overthrown in the wilderness" (1 Corinthians 10:5).
Let us pray for the Lord to open our eyes just as He did to the two disciples on the road to Emmaus, that we may see Christ and His Gospel proclaimed in every verse of the OT and no longer make a false dichotomy between the OT as "Law" (teaching salvation by works) and the NT as "Gospel" (teaching salvation by faith). Christ is proclaimed in the Law, the Prophets and the Psalms. But we need the Kingdom of God as the hermeneutical principle to be able to see it and not try to separate the Gospel in the OT from the Law like wheats from tares.
With the Kingdom perspective, we can preach the Law, Prophets and Psalms as the Gospel of Christ.
Father, open our eyes to love Your Scriptures, especially the OT for in it, You have already proclaimed Christ and His Gospel of the Kingdom. Amen.