What the Bible says about Scripture
(From Forerunner Commentary)
The word scripture refers to the Old Testament. Paul writes in a way where the Scripture is personified ("foreseeing"), but the intent is clear that the Scripture is being spoken of in terms of the Author. The One who inspired the Old Testament (Scripture) foresaw that God would justify the Gentiles through faith. This means that the doctrine of justification by faith is contained in the Old Testament (Psalm 130:3, 143:2; Exodus 34:7; Job 4:17, 9:2-3,29, 15:14, 25:4; Ecclesiastes 7:20), and is not something contained just in the New—if not directly, then at least indirectly by showing that we cannot justify ourselves in God's eyes. (God foretells of this Gentile justification in Isaiah 49:6, 22-23, 60.)
The phrase "would justify" is in the present indicative sense, which means that it is now, and at all times, God's one way of justification. Here it would better be translated as "justifies." God justifies through faith—He always has, and as long as the present order of things continues, He always will. There was never a time when a person could have been justified by their works or actions.
Faith in Christ is the means by which God would justify the heathens ("the nations"—the Gentiles), but that justification does not mean they were allowed to remain Gentiles (heathens) in a spiritual sense. Being justified does not mean we are told we have not done anything wrong. Being justified means we are brought into legal alignment with God and His law, so the sin-induced gulf between God and man can be overcome and the relationship can begin. The physical Gentiles are/were given the opportunity to repent (Acts 11:18), which coincides with justification, but even repentance means that a change in behavior (works) must be made. God saves us from our sins, not in our sins.
David C. Grabbe