The Abrahamic Covenant was made between God and Abraham. It did not involved anyone else.
I disagree. The Abrahamic covenant was always meant to be an everlasting covenant to be inherited by all of Abraham's seed (or descendants).
[Gen 15:5-6 NASB] 5 And He took him outside and said, "Now look toward the heavens, and count the stars, if you are able to count them." And He said to him, "So shall your descendants [seed, singular] be." 6 Then he believed in the LORD; and He reckoned it to him as righteousness.
Gen 17:4-10 NASB 4 "As for Me, behold, My covenant is with you, And you will be the father of a multitude of nations. 5 "No longer shall your name be called Abram, But your name shall be Abraham; For I have made you the father of a multitude of nations. 6 "I will make you exceedingly fruitful, and I will make nations of you, and kings will come forth from you. 7 "I will establish My covenant between Me and you and your descendants [seed, singular] after you throughout their generations for an everlasting covenant, to be God to you and to your descendants [seed, singlular] after you. 8 "I will give to you and to your descendants [seed, singular] after you, the land of your sojournings, all the land of Canaan, for an everlasting possession; and I will be their God." 9 God said further to Abraham, "Now as for you, you shall keep My covenant, you and your descendants [seed, singular] after you throughout their generations. 10 "This is My covenant, which you shall keep, between Me and you and your descendants [seed, singular] after you: every male among you shall be circumcised.
[Gal 3:6-9 NASB] 6 Even so Abraham BELIEVED GOD, AND IT WAS RECKONED TO HIM AS RIGHTEOUSNESS. 7 Therefore, be sure that it is those who are of faith who are sons of Abraham. 8 The Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, [saying,] "ALL THE NATIONS WILL BE BLESSED IN YOU." 9 So then those who are of faith are blessed with Abraham, the believer.
[Rom 4:11-17 NASB] 11 and he received the sign of circumcision, a seal of the righteousness of the faith which he had while uncircumcised, so that he might be the father of all who believe without being circumcised, that righteousness might be credited to them, 12 and the father of circumcision to those who not only are of the circumcision, but who also follow in the steps of the faith of our father Abraham which he had while uncircumcised. 13 For the promise to Abraham or to his descendants that he would be heir of the world was not through the Law, but through the righteousness of faith. 14 For if those who are of the Law are heirs, faith is made void and the promise is nullified; 15 for the Law brings about wrath, but where there is no law, there also is no violation. 16 For this reason [it is] by faith, in order that [it may be] in accordance with grace, so that the promise will be guaranteed to all the descendants, not only to those who are of the Law, but also to those who are of the faith of Abraham, who is the father of us all, 17 (as it is written, "A FATHER OF MANY NATIONS HAVE I MADE YOU") in the presence of Him whom he believed, [even] God, who gives life to the dead and calls into being that which does not exist.
The New Covenant was between the Father and Christ. Our faith in Christ as Saviour, set any Jewish believer free from the Mosaic Covenant, because in the terms of the New Covenant, Jesus kept the Law for all those who believed and embraced Him by faith. Jewish believers are not longer obliged to keep the Mosaic Covenant, because it was cancelled on the death of Christ.
What you don't realize is that the New Covenant is the Abrahamic covenant.
[Gal 3:16 NASB] 16 Now the promises were spoken to Abraham and to his seed. He does not say, "And to seeds," as [referring] to many, but [rather] to one, "And to your seed," that is, Christ.
Go back to Genesis 15-17 and whenever it uses the term (in the King James) "Seed"... it is singular and as Gal 3:16 says, it means God is talking about Jesus Christ. More modern translations translate the "Seed, singular" as "descendants." That Abrahamic covenant WAS God's covenant with Jesus Christ. The Abrahamic covenant is the "covenant of faith."
[Gal 3:14-17 NASB] 14 in order that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we would receive the promise of the Spirit through faith. 15 Brethren, I speak in terms of human relations: even though it is [only] a man's covenant, yet when it has been ratified, no one sets it aside or adds conditions to it. 16 Now the promises were spoken to Abraham and to his seed. He does not say, "And to seeds," as [referring] to many, but [rather] to one, "And to your seed," that is, Christ. 17 What I am saying is this: the Law, which came four hundred and thirty years later, does not invalidate a covenant previously ratified by God, so as to nullify the promise.
The Abrahamic Covenant would never apply to Jewish or Christian believers because it was made with Abraham, before the nation of Israel was originally founded.
I humbly disagree. Here is why:
[Rom 4:9-17 NASB] 9 Is this blessing then on the circumcised, or on the uncircumcised also? For we say, "FAITH WAS CREDITED TO ABRAHAM AS RIGHTEOUSNESS." 10 How then was it credited? While he was circumcised, or uncircumcised? Not while circumcised, but while uncircumcised; 11 and he received the sign of circumcision, a seal of the righteousness of the faith which he had while uncircumcised, so that he might be the father of all who believe without being circumcised, that righteousness might be credited to them, 12 and the father of circumcision to those who not only are of the circumcision, but who also follow in the steps of the faith of our father Abraham which he had while uncircumcised. 13 For the promise to Abraham or to his descendants that he would be heir of the world was not through the Law, but through the righteousness of faith. 14 For if those who are of the Law are heirs, faith is made void and the promise is nullified; 15 for the Law brings about wrath, but where there is no law, there also is no violation. 16 For this reason [it is] by faith, in order that [it may be] in accordance with grace, so that the promise will be guaranteed to all the descendants, not only to those who are of the Law, but also to those who are of the faith of Abraham, who is the father of us all, 17 (as it is written, "A FATHER OF MANY NATIONS HAVE I MADE YOU") in the presence of Him whom he believed, [even] God, who gives life to the dead and calls into being that which does not exist.
[Gal 4:22-28 NASB] 22 For it is written that Abraham had two sons, one by the bondwoman and one by the free woman. 23 But the son by the bondwoman was born according to the flesh, and the son by the free woman through the promise. 24 This is allegorically speaking, for these [women] are two covenants: one [proceeding] from Mount Sinai bearing children who are to be slaves; she is Hagar. 25 Now this Hagar is Mount Sinai in Arabia and corresponds to the present Jerusalem, for she is in slavery with her children. 26 But the Jerusalem above is free; she is our mother. 27 For it is written, "REJOICE, BARREN WOMAN WHO DOES NOT BEAR; BREAK FORTH AND SHOUT, YOU WHO ARE NOT IN LABOR; FOR MORE NUMEROUS ARE THE CHILDREN OF THE DESOLATE THAN OF THE ONE WHO HAS A HUSBAND." 28 And you brethren, like Isaac, are children of promise.
[Rom 2:28-29 NASB] 28 For he is not a Jew who is one outwardly, nor is circumcision that which is outward in the flesh. 29 But he is a Jew who is one inwardly; and circumcision is that which is of the heart, by the Spirit, not by the letter; and his praise is not from men, but from God.
[Eph 1:13-14 NASB] 13 In Him, you also, after listening to the message of truth, the gospel of your salvation--having also believed, you were sealed in Him with the Holy Spirit of promise, 14 who is given as a pledge of our inheritance, with a view to the redemption of [God's own] possession, to the praise of His glory.
The Abrahamic covenant IS the covenant of faith... it IS the covenant God makes with Christ. It was made to to Abraham and to his seed (singular), meaning Christ. Having just said the "seed" (singular) that the promise was made to was Christ in Gal 3:16, it says:
[Gal 3:18-19 NASB] 18 For if the inheritance is based on law, it is no longer based on a promise; but God has granted it to Abraham by means of a promise. 19 Why the Law then? It was added because of transgressions, having been ordained through angels by the agency of a mediator, until the seed would come to whom the promise had been made.
The "seed to whom the promise had been made" was Christ. This is interesting... it means the covenant of faith pre-dates the covenant of The Law. Look up above in Galatians 3:17; it says the law came 430 years after the covenant of faith was ratified, and that once ratified it can no longer have conditions added to it. This means the covenant of faith was given when The Law didn't exist. It is truly apart from The Law. What it also means is that The Law has never existed apart from the covenant of faith... and The Law can testify about the covenant of faith. For example:
[Deu 30:6 NASB] 6 "Moreover the LORD your God will circumcise your heart and the heart of your descendants, to love the LORD your God with all your heart and with all your soul, so that you may live.
[Deu 30:11-16, 19 NASB] 11 "For this commandment which I command you today is not too difficult for you, nor is it out of reach. 12 "It is not in heaven, that you should say, 'Who will go up to heaven for us to get it for us and make us hear it, that we may observe it?' 13 "Nor is it beyond the sea, that you should say, 'Who will cross the sea for us to get it for us and make us hear it, that we may observe it?' 14 "But the word is very near you, in your mouth and in your heart, that you may observe it. 15 "See, I have set before you today life and prosperity, and death and adversity; 16 in that I command you today to love the LORD your God, to walk in His ways and to keep His commandments and His statutes and His judgments, that you may live and multiply, and that the LORD your God may bless you in the land where you are entering to possess it. ... 19 "I call heaven and earth to witness against you today, that I have set before you life and death, the blessing and the curse. So choose life in order that you may live, you and your descendants,
[Rom 10:4-10 NASB] 4 For Christ is the end of the law for righteousness to everyone who believes. 5 For Moses writes that the man who practices the righteousness which is based on law shall live by that righteousness. 6 But the righteousness based on faith speaks as follows: "DO NOT SAY IN YOUR HEART, 'WHO WILL ASCEND INTO HEAVEN?' (that is, to bring Christ down), 7 or 'WHO WILL DESCEND INTO THE ABYSS?' (that is, to bring Christ up from the dead)." 8 But what does it say? "THE WORD IS NEAR YOU, IN YOUR MOUTH AND IN YOUR HEART"--that is, the word of faith which we are preaching, 9 that if you confess with your mouth Jesus [as] Lord, and believe in your heart that God raised Him from the dead, you will be saved; 10 for with the heart a person believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation.