Galatians 3:8 (ESV) … “And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, “In you shall all the nations be blessed.”
Paul reminds us of something foreseen long ago by Holy Scripture: ‘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” [a quotation from Genesis 12:3]’ (v. 8).
The New Testament interprets this for us. A Savior would come in Abraham’s line. In and by the gospel he would be presented to all the nations as an object of saving faith, and people would believe in him and be justified. That is what was foreseen and announced. And it has happened! Justification by faith, the doctrine with a long history, has come to have, as it were, a wide geography. It is being preached in every corner of the globe, and wherever it goes it both announces rich blessing for sinners and communicates it to everyone who believes. It did so in Gentile Galatia. By faith in the Jesus whom Paul preached to them, the Galatians fell heirs to the same blessing of justification that Abraham enjoyed.
It is no different today. All over the world, helpless sinners are hearing of a Saviour to whom they can go in their desperate need, a Savior who pardons them and clothes them with his perfect righteousness the moment they believe in him. 
 Campbell, D. (2009). Opening Up Galatians (pp. 54–55). Leominster: Day One Publications.