Just as the New Testament is the fulfillment of the Old Testament; so is Jesus' sacrifice a fulfillment of the old covenant. A covenant must be fulfilled by the shedding of blood. Prior to Jesus' sacrifice, the fulfillment was throught the sacrifices made through the temple. These sacrifices served as a shadow of the sacrifice that was the substance. Once the fulfillment was made in substance, the ordinances of the sacrifices made in the temple were to cease. They were saved by the shedding of the blood of the lamb, with the promise that there would be the fulfillment to come from the shedding of blood from our Savior. We are saved by His sacrifice, fulfilling the promise of the original covenant - unchanged and everlasting. The only difference is the fulfillment thereof. They were saved by their obedience to the promise, and we are saved by the faith in the fulfillment of the promise. Thus, the ordinances of Moses concerning the sacrifices and feast days (yearly sabbaths) have been put away, being completes through Jesus; but the law of God will stand forever. It is a reflection of his unchanginging Love. Jesus Himself said about His own laws, 'Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven.' Matthew 5:19 KJV