since indeed it is one [and the same] God who will justify the circumcised by faith [which began with Abraham] and the uncircumcised through [their newly acquired] faith.

Justification by Faith Evidenced in Old Testament

What then shall we say that Abraham, our forefather humanly speaking, has found? [Has he obtained a favored standing?]

So understand that it is the people who live by faith [with confidence in the power and goodness of God] who are [the true] sons of Abraham.

The Scripture, foreseeing that God would justify the Gentiles by faith, proclaimed the good news [of the Savior] to Abraham in advance [with this promise], saying, “In you shall all the nations be blessed.”

So then those who are people of faith [whether Jew or Gentile] are blessed and favored by God [and declared free of the guilt of sin and its penalty, and placed in right standing with Him] along with Abraham, the believer.

By faith Abraham, when he was called [by God], obeyed by going to a place which he was to receive as an inheritance; and he went, not knowing where he was going.

By faith Abraham, when he was tested [that is, as the testing of his faith was still in progress], offered up Isaac, and he who had received the promises [of God] was ready to sacrifice his only son [of promise];

Was our father Abraham not [shown to be] justified by works [of obedience which expressed his faith] when he offered Isaac his son on the altar [as a sacrifice to God]?

And the Scripture was fulfilled which says, “Abraham believed God, and this [faith] was credited to him [by God] as righteousness and as conformity to His will,” and he was called the friend of God.