John Calvin - following the ancient theologians - believed that the Old Testament saints were united with Christ and saved by Him (through faith which is God's gift). The Old Testament is the "exhibition" of the gospel hidden behind a curtain of symbols, images and shadows. Even if only for that reason we should have a closer look at the content, structure and symbolism.
Old Testament stories are connected with one another. For example, we will not understand the description of David's life unless we know the story of Moses. We will not understand the story of Moses if we don’t know the events of Noah's time. We will not understand Ezekiel if we don’t know what the Temple looked like. We will not understand the symbolism of the construction of the Temple without knowing what the Garden of Eden and the world were designed by God in the first two chapters of the Bible.
Unfortunately, many Christians today do not really know what to do with the Old Testament. The liberal theology of the nineteenth century separated the New Testamnet from the Old Testament completely; Similarly, Marcion, the heretic, taught that God of the New Testament is quite different than Jehovah God of the Old Testament.
Of course, if we are Christians we should remember that we live with "every word" (Matthew 4:4, 2 Timothy 3:16) coming from God, including 39 books of the original Scriptures of the Old Testament. When we ignore the teachings of Moses, the Psalms and the prophets, Christianity is brought to the role of an intimate, unverifiable religion, subjective feeling, something that has little to do with the real world. Such thinking has little in common with the core and essence of the Gospel.