Some of the following is a bit advanced.
Even many who assert they hold to MAD; are unaware of it and and as result; end up at other ideas.
There were the Believing remnant of Israel: who had believed before God concluded the rest in Unbelief (in other words; having continued in the UNcircumcision of heart of their fathers).
Said Believing remnant were sealed by God just before He concluded the rest in unbelief, and cut them (those in unbelief) off from their access to their blessing as Israelites.
Romans 11:7 What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded.
These Israelites in Unbelief were now UNcircumcision; under sin, or no better off then the Gentiles - for their having refused to believe both the assertion of Jesus and the Twelve, that He was the very Chris the Law and the Prophets did say should come.
Romans 9:32 Wherefore? Because they sought it not by faith, but as it were by the works of the law. For they stumbled at that stumblingstone; 9:33 As it is written, Behold, I lay in Sion a stumblingstone and rock of offence: and whosoever believeth on him shall not be ashamed.
In contrast were their Believing Remnant...
Romans 10:19 But I say, Did not Israel know? First Moses saith, I will provoke you to jealousy by them that are no people, and by a foolish nation I will anger you. 10:20 But Esaias is very bold, and saith, I was found of them that sought me not; I was made manifest unto them that asked not after me. 10:21 But to Israel he saith, All day long I have stretched forth my hands unto a disobedient and gainsaying people.
They were these and their converts...
John 1:45 Philip findeth Nathanael, and saith unto him, We have found him, of whom Moses in the law, and the prophets, did write, Jesus of Nazareth, the son of Joseph.
1:49 Nathanael answered and saith unto him, Rabbi, thou art the Son of God; thou art the King of Israel.
1:51 And he saith unto him, Verily, verily, I say unto you, Hereafter ye shall see heaven open, and the angels of God ascending and descending upon the Son of man.
Said Believing Remnant not only believed the Law and the Prophets that Jesus was the Christ, but continued to keep the Law.
Albeit, no longer FOR righteousness, but because of THEIR Prophesied Grace.
Which Promised they would one day be able to keep the Law, because the Law is their Identity as the Israel of God in the site of the nations.
Deuteronomy 4:5 Behold, I have taught you statutes and judgments, even as the LORD my God commanded me, that ye should do so in the land whither ye go to possess it. 4:6 Keep therefore and do them; for this is your wisdom and your understanding in the sight of the nations, which shall hear all these statutes, and say, Surely this great nation is a wise and understanding people. 4:7 For what nation is there so great, who hath God so nigh unto them, as the LORD our God is in all things that we call upon him for? 4:8 And what nation is there so great, that hath statutes and judgments so righteous as all this law, which I set before you this day?
Jeremiah 31:31 Behold, the days come, saith the LORD, that I will make a new covenant with the house of Israel, and with the house of Judah: 31:32 Not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the LORD: 31:33 But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people. 31:34 And they shall teach no more every man his neighbour, and every man his brother, saying, Know the LORD: for they shall all know me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more. 31:35 Thus saith the LORD, which giveth the sun for a light by day, and the ordinances of the moon and of the stars for a light by night, which divideth the sea when the waves thereof roar; The LORD of hosts is his name: 31:36 If those ordinances depart from before me, saith the LORD, then the seed of Israel also shall cease from being a nation before me for ever. 31:37 Thus saith the LORD; If heaven above can be measured, and the foundations of the earth searched out beneath, I will also cast off all the seed of Israel for all that they have done, saith the LORD.
This was why they had all been able to be on the same page in all things, in early Acts - because "as many as recieved Him gave He power to become the sons of God" John 1:12, He had called that nation to be, when He gave them their Law as their "wisdom in the sight of the nations."
In contrast, the rest had been of this type...
John 5:43 I am come in my Father's name, and ye receive me not: if another shall come in his own name, him ye will receive. 5:44 How can ye believe, which receive honour one of another, and seek not the honour that cometh from God only? 5:45 Do not think that I will accuse you to the Father: there is one that accuseth you, even Moses, in whom ye trust. 5:46 For had ye believed Moses, ye would have believed me: for he wrote of me. 5:47 But if ye believe not his writings, how shall ye believe my words?
With the raising up of Paul; said lost Jews were given access once more, but to a blessing now, that was absent of Israel's Believing Remnant's Promises, now on hold, til the fullness of what was now a Gentile blessing be come in, that God was now offering both lost Jews and Gentiles, on a level.play field.
Romans 3:9 What then? are we better than they? No, in no wise: for we have before proved both Jews and Gentiles, that they are all under sin; 3:10 As it is written, There is none righteous, no, not one: 3:11 There is none that understandeth, there is none that seeketh after God.
These Jews were not of Israel's Believing Remnant, as said remnant had been sealed by God; their Promises put on hold; the rest cut off from that.
In the following, we see these various kinds of Israelites...
1- James and those with him as the Israel of God (Believing Remnant under the Law);
2 - the Apostle Paul as the first Israelite in UNcircumcision who went from said status to being the first member of God's New Creature: the Body of Christ; and those Israelites saved after Paul and whom he was teaching were not under the Law;
3- and those Israelites who remained in Unbelief and who now opposed Paul..,
Acts 21:17 And when we were come to Jerusalem, the brethren received us gladly. 21:18 And the day following Paul went in with us unto James; and all the elders were present. 21:19 And when he had saluted them, he declared particularly what things God had wrought among the Gentiles by his ministry. 21:20 And when they heard it, they glorified the Lord, and said unto him, Thou seest, brother, how many thousands of Jews there are which believe; and they are all zealous of the law: 21:21 And they are informed of thee, that thou teachest all the Jews which are among the Gentiles to forsake Moses, saying that they ought not to circumcise their children, neither to walk after the customs. 21:22 What is it therefore? the multitude must needs come together: for they will hear that thou art come. 21:23 Do therefore this that we say to thee: We have four men which have a vow on them; 21:24 Them take, and purify thyself with them, and be at charges with them, that they may shave their heads: and all may know that those things, whereof they were informed concerning thee, are nothing; but that thou thyself also walkest orderly, and keepest the law. 21:25 As touching the Gentiles which believe, we have written and concluded that they observe no such thing, save only that they keep themselves from things offered to idols, and from blood, and from strangled, and from fornication. 21:26 Then Paul took the men, and the next day purifying himself with them entered into the temple, to signify the accomplishment of the days of purification, until that an offering should be offered for every one of them.
You see this here, by the way?
Acts 21:21 And they are informed of thee, that thou teachest all the Jews which are among the Gentiles to forsake Moses, saying that they ought not to circumcise their children, neither to walk after the customs.
That is this kind of thing here...
Romans 7:4 Wherefore, my brethren, ye also are become dead to the law by the body of Christ; that ye should be married to another, even to him who is raised from the dead, that we should bring forth fruit unto God. 7:5 For when we were in the flesh, the motions of sins, which were by the law, did work in our members to bring forth fruit unto death. 7:6 But now we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not in the oldness of the letter.