Abraham became righteous without the Law and even before circumcision:
“just as David also describes the blessedness of the man to whom God imputes righteousness apart from works: ‘Blessed are those whose lawless deeds are forgiven, and whose sins are covered; blessed is the man to whom the LORD shall not impute sin.’ Does this blessedness then come upon the circumcised only, or upon the uncircumcised also? For we say that faith was accounted to Abraham for righteousness. How then was it accounted? While he was circumcised, or uncircumcised? Not while circumcised, but while uncircumcised. And he received the sign of circumcision, a seal of the righteousness of the faith which he had while still uncircumcised, that he might be the father of all those who believe, though they are uncircumcised, that righteousness might be imputed to them also, and the father of circumcision to those who not only are of the circumcision, but who also walk in the steps of the faith which our father Abraham had while still uncircumcised. For the promise that he would be the heir of the world was not to Abraham or to his seed through the law, but through the righteousness of faith. For if those who are of the law are heirs, faith is made void and the promise made of no effect, because the law brings about wrath; for where there is no law there is no transgression. Therefore it is of faith that it might be according to grace, so that the promise might be sure to all the seed, 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 (as it is written, ‘I have made you a father of many nations’) in the presence of Him whom he believed — God, who gives life to the dead and calls those things which do not exist as though they did” (Rom. 4:6-17)
“When Abram was ninety-nine years old, the LORD appeared to Abram and said to him, ‘I am Almighty God; walk before Me and be blameless. <...> As for Me, behold, My covenant is with you, and you shall be a father of many nations. No longer shall your name be called Abram, but your name shall be Abraham; for I have made you a father of many nations’” (Gen. 17:1,4-5)
Believers are the sons of Abraham:
“just as Abraham ‘believed God, and it was accounted to him for righteousness.’ Therefore know that only those who are of faith are sons of Abraham. And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel to Abraham beforehand, saying, ‘In you all the nations shall be blessed.’ So then those who are of faith are blessed with believing Abraham. For as many as are of the works of the law are under the curse; for it is written, ‘Cursed is everyone who does not continue in all things which are written in the book of the law, to do them.’ But that no one is justified by the law in the sight of God is evident, for ‘the just shall live by faith.’ Yet the law is not of faith, but ‘the man who does them shall live by them.’ Christ has redeemed us from the curse of the law, having become a curse for us (for it is written, ‘Cursed is everyone who hangs on a tree’), that the blessing of Abraham might come upon the Gentiles in Christ Jesus, that we might receive the promise of the Spirit through faith. Brethren, I speak in the manner of men: Though it is only a man’s covenant, yet if it is confirmed, no one annuls or adds to it. Now to Abraham and his Seed were the promises made. He does not say, ‘And to seeds,’ as of many, but as of one, ‘And to your Seed,’ who is Christ. <...> For as many of you as were baptized into Christ have put on Christ. <...> And if you are Christ’s, then you are Abraham’s seed, and heirs according to the promise” (Gal. 3:6-16,27,29)
“I will bless those who bless you, and I will curse him who curses you; and in you all the families of the earth shall be blessed” (Gen. 12:3)
“that the blessing of Abraham might come upon the Gentiles in Christ Jesus, that we might receive the promise of the Spirit through faith” (Gal. 3:14)
Jesus Christ on the Children of Abraham:
“and do not think to say to yourselves, ‘We have Abraham as our father.’ For I say to you that God is able to raise up children to Abraham from these stones” (Matt. 3:9; Luke. 3:8)
The Church Is the New Israel
“But you are a chosen generation, a royal priesthood, a holy nation, His own special people, that you may proclaim the praises of Him who called you out of darkness into His marvelous light; who once were not a people but are now the people of God, who had not obtained mercy but now have obtained mercy” (1 Pet. 2:9-10)