3.1 What advantage then hath the Jew? or what profit is there of circumcision?
And Romans 3:19 Now we know that what things soever the law saith, it saith to them who are under the law: that every mouth may be stopped, and all the world may become guilty before God.
20 Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
21 But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets;
27 Where is boasting then? It is excluded. By what law? of works? Nay: but by the law of faith.
28 Therefore we conclude that a man is justified by faith without the deeds of the law.
31 Are we then annulling the law by this faith? Of course not! On the contrary, we are supporting the law.
It hits over and over again that this is about the LAW of the Pharisee-Jews and they are no longer applicable to the Jesus-movement-Jews.
Over and Over again and then he brings up Abraham in the next chapter about the works of The Law.
You keep on ignoring Christ's teachings that He gives salvation and you justify yourself by "eating of His body", by baptism, by penance and by enduring to the end.
Indeed, and as just shown you, you simply do not get it that the Law represents the supreme form of justification based upon merit of works, and broadly disallows "works of righteousness" as giving life and appropriating justification, and which is a present condition.
Moreover, Abraham was not first justified when he offered up Issac, (Gn. 22) but way before that when his faith was counted for righteousness. (Gn. 15:6) Faith in the heart justifies one and the confession of this faith which follows confirms one is of complete, salvific faith. (cf. Romans 10:9-13)