"Though this covenant was made with Adam and renewed to Abraham, it could not be ratified until the death of Christ. It had existed by the promise of God since the first intimation of redemption had been given; it had been accepted by faith; yet when ratified by Christ, it is called a new covenant. The law of God was the basis of this covenant, which was simply an arrangement for bringing men again into harmony with the divine will, placing them where they could obey God’s law."
What Is The Difference Between The Two Covenants?
The "New" Covenant was initially given to Adam and Eve, renewed to Abraham and ratified when Christ died. It could accordingly be called the "original" covenant. The "Old" Covenant, provided to Moses on Mt. Sinai, was given to lead people to feel the need of the Saviour and point them forward to the Covenant promised to Abraham—eventually called the "New" Covenant because it was ratified by Christ even though it was given prior to the one being given to Moses.
The "new" covenant derives the "new" label from Christ having ratified it in His blood at the time of the crucifixion.
Genesis 22:18 "And in thy seed shall all the nations of the earth be blessed; because thou hast obeyed my voice."
Galatians 3:8 "And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed."
Galatians 3:16 "Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ."
Genesis 17:1 "And when Abram was ninety years old and nine, the Lord appeared to Abram, and said unto him, I am the Almighty God; walk before me, and be thou perfect. 2 And I will make my covenant between me and thee, and will multiply thee exceedingly."
Exodus 19:5 "Now therefore, if ye will obey my voice indeed, and keep my covenant, then ye shall be a peculiar treasure unto me above all people: for all the earth is mine: 6 And ye shall be unto me a kingdom of priests, and an holy nation. These are the words which thou shalt speak unto the children of Israel."
Exodus 19:7 "And Moses came and called for the elders of the people, and laid before their faces all these words which the Lord commanded him. 8 And all the people answered together, and said, All that the Lord hath spoken we will do. And Moses returned the words of the people unto the Lord."
Exodus 24:7 "And he took the book of the covenant, and read in the audience of the people: and they said, All that the Lord hath said will we do, and be obedient."
"The covenant of grace was first made with man in Eden, when after the Fall there was given a divine promise that the seed of the woman should bruise the serpent’s head. To all men this covenant offered pardon and the assisting grace of God for future obedience through faith in Christ. It also promised them eternal life on condition of fidelity to God’s law. Thus the patriarchs received the hope of salvation. {PP 370.2}
"This same covenant was renewed to Abraham in the promise, “In thy seed shall all the nations of the earth be blessed.” Genesis 22:18. This promise pointed to Christ. So Abraham understood it (see Galatians 3:8, 16), and he trusted in Christ for the forgiveness of sins. It was this faith that was accounted unto him for righteousness. The covenant with Abraham also maintained the authority of God’s law. The Lord appeared unto Abraham, and said, “I am the Almighty God; walk before Me, and be thou perfect.” Genesis 17:1. The testimony of God concerning His faithful servant was, “Abraham obeyed My voice, and kept My charge, My commandments, My statutes, and My laws.” Genesis 26:5. And the Lord declared to him, “I will establish My covenant between Me and thee and thy seed after thee in their generations, for an everlasting covenant, to be a God unto thee and to thy seed after thee.” Genesis 17:7. {PP 370.3}
"Though this covenant was made with Adam and renewed to Abraham, it could not be ratified until the death of Christ. It had existed by the promise of God since the first intimation of redemption had been given; it had been accepted by faith; yet when ratified by Christ, it is called a new covenant. The law of God was the basis of this covenant, which was simply an arrangement for bringing men again into harmony with the divine will, placing them where they could obey God’s law." {PP 370.4}
"Another compact—called in Scripture the “old” covenant—was formed between God and Israel at Sinai, and was then ratified by the blood of a sacrifice. The Abrahamic covenant was ratified by the blood of Christ, and it is called the “second,” or “new,” covenant, because the blood by which it was sealed was shed after the blood of the first covenant. That the new covenant was valid in the days of Abraham is evident from the fact that it was then confirmed both by the promise and by the oath of God—the “two immutable things, in which it was impossible for God to lie.” Hebrews 6:18. {PP 371.1}
"But if the Abrahamic covenant contained the promise of redemption, why was another covenant formed at Sinai? In their bondage the people had to a great extent lost the knowledge of God and of the principles of the Abrahamic covenant. In delivering them from Egypt, God sought to reveal to them His power and His mercy, that they might be led to love and trust Him. He brought them down to the Red Sea—where, pursued by the Egyptians, escape seemed impossible—that they might realize their utter helplessness, their need of divine aid; and then He wrought deliverance for them. Thus they were filled with love and gratitude to God and with confidence in His power to help them. He had bound them to Himself as their deliverer from temporal bondage. {PP 371.2}
"But there was a still greater truth to be impressed upon their minds. Living in the midst of idolatry and corruption, they had no true conception of the holiness of God, of the exceeding sinfulness of their own hearts, their utter inability, in themselves, to render obedience to God’s law, and their need of a Saviour. All this they must be taught. {PP 371.3}
"God brought them to Sinai; He manifested His glory; He gave them His law, with the promise of great blessings on condition of obedience: “If ye will obey My voice indeed, and keep My covenant, then ... ye shall be unto Me a kingdom of priests, and an holy nation.” Exodus 19:5, 6. The people did not realize the sinfulness of their own hearts, and that without Christ it was impossible for them to keep God’s law; and they readily entered into covenant with God. Feeling that they were able to establish their own righteousness, they declared, “All that the Lord hath said will we do, and be obedient.” Exodus 24:7. They had witnessed the proclamation of the law in awful majesty, and had trembled with terror before the mount; and yet only a few weeks passed before they broke their covenant with God, and bowed down to worship a graven image. They could not hope for the favor of God through a covenant which they had broken; and now, seeing their sinfulness and their need of pardon, they were brought to feel their need of the Saviour revealed in the Abrahamic covenant and shadowed forth in the sacrificial offerings. Now by faith and love they were bound to God as their deliverer from the bondage of sin. Now they were prepared to appreciate the blessings of the new covenant." {PP 371.4}
Reasons for confusion:
1. The "New" Covenant is actually the original covenant given to Adam and Eve, and later reaffirmed to Abraham.
2. The "New" Covenant includes everything the "Old" Covenant contained, but whereas the "Old" Covenant was written by God's finger on stone, the "New" Covenant is written by God on the tables of the heart.
The thoughts coming from Patriarchs and Prophets makes what could be a complicated subject exceedingly easy to understand.