Very good question from Nortones. We see the OT and NT as being God's integrated and harmonized revelation. God's redemptive plan is foreshadowed throughout the OT and brought to fulfillment in the NT. Christ and the Apostles explain the meaning of the law and how God redeems us through the Atonement.
The Bible is really about Christ. Humans were created to be in perfect harmony with God, but were disobedient, trusting ourselves more than Him. The redemptive work began there, through Abraham's line; through Israel, through the commands of the law, faithfulness to the only true God, obedience in faith; through the prophets, promisng redemption not only for Israel but for the world; to fulfillment in Christ, who reconciles us to God by His death, through faith by grace and obedience.