Having made the point in 3.1-5 that faith and grace > law and legalism Paul now goes way back for a supporting point and person.
“Just as Abraham believed God, and it was credited to him as righteousness, so then, understand that those who believe are the sons of Abraham. And the scripture, foreseeing that God would justify the Gentiles by faith, proclaimed the gospel to Abraham ahead of time, saying, “All the nations will be blessed in you.” So then those who believe are blessed along with Abraham the believer”.
As the Judaizers thought they were backed-up by what we would call the Old Testament, in particular Moses, Paul now goes even further back in support for the truth. He goes to Abraham and says that just as he believed God, and it was credited to him as righteousness, this is how you are viewed as righteous by God, not by works (cf. Genesis 15.6). The key point for Paul – and for you and me – is that Abraham’s justification came by hearing the Good News (the scripture…proclaimed the gospel to Abraham ahead of time…) and believing the Lord.
This came before any signs of outward devotion (Genesis 17.24). When we see the pattern and the order of how this happened it’s clear that the Judaizers are wrong in saying that circumcision (or any other religiously motivated work) was required and essential in order to be accepted (justified) by God.
What does this mean for you and me then? Well, it means that to be counted as sons of Abraham, to be blessed along with Abraham, all we need to do is believe. As Paul writes, Scripture has always foreseen that non-Jews would be justified by faith alone (v.8). Take this as a point to ponder today, something to think over: