Rom 4:6-9, Ps 32:1, Jn 8:56, Gen 22:18, Gal 3:16
Abraham was justified by faith in the coming Christ before he was circumcised. (Rom 4:1-3, 6-9, Ps 32:1)
Rom 4:1 What shall we say then that Abraham our father, as pertaining to the flesh, hath found? 2 For if Abraham were justified by works, he hath whereof to glory; but not before God. 3 For what saith the scripture? Abraham believed God, and it was counted unto him for righteousness. 6 Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works, 7 Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered. 8 Blessed is the man to whom the Lord will not impute sin. 9 Cometh this blessedness then upon the circumcision only, or upon the uncircumcision also? for we say that faith was reckoned to Abraham for righteousness.
Ps 32:1 Blessed is he whose transgression is forgiven, whose sin is covered.
Abraham believed and rejoiced in the coming of Christ, the seed of Abraham that God had promised. (Jn 8:56, Gen 22:18, Gal 3:16)
Jn 8:56 Your father Abraham rejoiced to see my day: and he saw it, and was glad.
Gen 22:18 And in thy seed shall all the nations of the earth be blessed; because thou hast obeyed my voice.
Gal 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.