After suggesting that covenant is what ties the whole Bible together, Dr. Johnson writes that
every historical narrative in Israel's ancient Scriptures attests to the need not only for the Lord's gracious intervention on behalf of the undeserving but also for the arrival in history of a flawless human Servant to fulfill our part of the bargain. Jesus is the gracious Lord who is also the well-pleasing obedient Servant. This discovery opens to us the connection of every event recounted in the Bible to Jesus the mediator of the new and better covenant (Heb. 7:22; 12:24). . . .See Dennis Johnson's book-length treatment of Christ-centered preaching here.
Jesus is both the Law-giving Lord and the Law-keeping Servant, uniquely authorized to inherit every covenant blessing as the one--the only one--who has loved the Lord his God with all his heart, soul, strength, and mind, and his neighbor as himself (Matt. 22:37-39). This discovery opens to us the connection of every command in Scripture to the Christ who kept it for us and who now conforms our hearts to it by his quiet, relentless life-giving Holy Spirit.