The New Covenant is poorly understood today. Part of the problem is terminology. A covenant in today’s parlance involves obligations from both parties of an agreement. The covenants spoken of in the bible are not a covenant like we think of today. It is a testament of benefits to those in Christ. Christ has died and left a will to the beneficiaries. A testament records the tangible things we have in Christ and are recorded in 27 books, which comprise Gospels, letters, and a historical narrative (Acts of the Apostles). Christians refer to these books as the New Testament. This is good terminology as long as it is understood properly. The actual New Testament is The New Covenant which was promised in Jer, 31.31 and many other places in the O.T. It is correct to say the 27 books list the benefits of Christ’s will to the beneficiaries and are The New Covenant. They are the sole authority for all matters of faith and practice for the beneficiary: the Christian. Church officers, creeds, confessions are all subject to the words of scripture finally contained in the 27 books of The New Testament.
The Old (Mosaic) Covenant was very similar to the New Covenant because the benefits were forgiveness and fellowship. When the bible speaks of The Law of Moses, for the most part, it speaks of the regulations concerning the Jewish Temple, Aaronic Priesthood, and of the sacrifices. Everyone broke the regulations of the Mosaic Law, such as the Ten Commandments and other performance rules, either internally or externally. This is why heart-circumcision was needed (see Gen. 17 where circumcision is inaugurated and described as a “sign”) and not only the external rite. The Law of Moses consisted of the prescribed means of restoring fellowship with God who would in turn bless them. It did not consist of keeping the ethical rules more perfectly as the way for acceptance. Instead, the Law of Moses presented shadows (Heb. 8.5) of Christ in the cultic aspects (Temple culture: the care in keeping the true representation) of the priesthood, the festivals and Sabbaths, and, most of all, the sacrifices.
The clearest description of a covenant is Heb. 9.16-18 where a will is discussed. The word “will” is the same as “covenant” elsewhere: diatheke. It speaks of a covenant being in force only after the death of the party who made it. Both the Old and New Covenants were represented by the substitutionary death of an innocent victim. The book of Hebrews, especially ch. 9, defines a covenant. Covenant sacrifice established a relationship with God and was inaugurated immediately after the Fall in Eden. Also, Christ’s priesthood resembled Melchizedek’s who may have embodied a sacrifice (apparent deadly wounds) since he had neither beginning or end of days; therefore, he could forecast atonement by means of an indestructible life. Hence, this theopany (Melchizedek) could bring out bread and wine (like the symbols of The New Covenant) because a relationship and fellowship with Abraham was already established. Likewise, only Christians are allowed to partake in the bread and wine of The Lord’s Supper.