The radical conclusion drawn from Genesis 15:6 is confirmed by a second quotation: The Scripture foresaw that God would justify the Gentiles by faith, and announced the gospel in advance to Abraham: "All nations will be blessed through you" (v. 8). It was not enough to show that those who believe are the children of Abraham. Paul proves that the principle of righteousness by faith attested for Abraham in Genesis 15:6 is explicitly extended by Scripture itself to the Gentiles. In Paul's quotation the phrase all nations from Genesis 18:18 is inserted in place of the phrase "all the families" (NIV "all peoples") in Genesis 12:3. This combination of texts in his quotation indicates that Paul's primary purpose is to demonstrate that Scripture witnesses to the inclusion of the Gentiles in the blessing promised to Abraham.

Paul interprets the promise of the blessing of all Gentiles in Abraham as a prophecy of what actually happened in his mission to the Gentiles. We must not forget that Paul wrote this letter as a missionary. He was called to take the good news about Jesus to the Gentiles. When he did so, he saw the incontestable evidence that God accepted the Gentiles who believed the gospel. It was clear that God justified them by faith. The evidence that this had happened was the bestowal of the Spirit on these Gentile converts. Paul had learned from his missionary experience that God would justify the Gentiles by faith (v. 8). In the light of that missionary experience, Paul understood the Old Testament promise of blessing for the Gentiles as a description and validation of his ministry.

Scripture foresaw what happened to the Gentile believers in Galatia. And because Scripture foresaw that God would justify Gentiles when they believed the gospel, Scripture announced the gospel in advance to Abraham. The gospel announced in advance to Abraham was a gospel of blessing for Gentiles. That was the gospel Paul preached to the Gentiles! To say that Scripture foresaw and announced the gospel in advance is to personify Scripture. The written text is treated as a person who sees and speaks. Paul's personification of Scripture means that for him the written text expresses the voice of God: what Scripture says, God says.