"As Christians we will always be looking at the Old Testament from the standpoint of the New Testament - from the framework of the gospel which is the goal of the Old Testament. But since the New Testament continually presupposes the Old Testament as a unity we, who are not acquainted with the Old Testament in the way the first Christians were, will be driven back to study the Old Testament on its own terms. To understand the whole living process of redemptive history in the Old Testament we must recognize two basic truths. The first is that salvation history is a process. The second is that this process of redemptive history finds its goal, its focus and fulfillment in the person and work of Christ." (Graeme Goldsworthy, Gospel and Kingdom, Paternoster Press, page 20, emphasis mine.)
Goldsworthy goes on to point out, rightfully I believe, that much of what we have today is a down-graded gospel that focuses on personal spiritual experience rather than on Jesus. "[The gospel] is the good news about Jesus, before it can become good news for sinful men and women. Indeed, it is only as the objective (redemptive-historical) facts are grasped that the subjective experience of the individual Christian can be understood." (page 21.)
Our focus should be on Christ, not ourselves. We therefore need to reorient our thinking on all the Scriptures and not just the New Testament. To see and try to live out our Christianity with little or no understanding of the Old Testament is like jumping to the middle of a novel. We can't expect to enjoy the book if we skip ove the first several chapters - important facts leading up to the culmination of the story are missing. So it is when we neglect the study of the Old Testament.
Allow me to suggest reading Goldsworthy's "Gospel and Kingdom" as a great starting point to gain understanding in this area. Tolle Lege