Galatians 3:6-9

Now the Lord had said unto Abram, Get thee out of thy country, and from thy kindred, and form thy father’s house, unto a land that I will shew thee: And I will make of thee a great nation, and I will bless thee, and make thy name great; and thou shalt be a blessing: And I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed. – Genesis 12:1-3
And he brought him forth abroad, and said, Look now toward heaven, and tell the stars, if thou be able to number them: and he said unto him, So shall thy seed be. And he believed in the Lord; and he counted it to him for righteousness. – Genesis 15:5-6

In Genesis, God made a covenant with Abraham. A covenant is simply a promise or an agreement. The Abrahamic Covenant, as it would come to be called, had two incredibly important parts – 1) Through the descendents of Abraham, all the families of the world [people groups] would be blessed; 2) Because Abraham believed God, God counted Abraham as righteous. Most covenants were an agreement between two parties whereby both agreed to do something to fulfill the terms of the agreement. The Abrahamic Covenant was exceptional in one regard, only one of the parties in the covenant, God, was going to be doing something to guarantee the covenant. God made it clear that it was Abraham’s duty to simply believe God.
As Abraham had descendants and heirs, the covenant passed on to them. The descendants of Abraham that would join the covenant with God were to be known not as much for their genetic relation to Abraham; instead, they were to be known, like Abraham, for their faith in God. Consistently through the Old Testament, the physical descendants of Abraham acted in ways that were atrocious and disobedient to God, but all the while they claimed that because they were physical descendants of Abraham, God should bless them. God sent prophets, priests, and even kings to call them to repent and turn in faith back to God, but time and again, the physical descendants refused to confess their need for their covenant-making God.
When we arrive in the New Testament, the physical descendants of Abraham were still convinced that by blood they should receive the blessing of God. They failed to acknowledge that it wasn’t anything in and of themselves that would bring the grace of God upon them. God was willing to freely extend blessing, but it would only come to those who would obey the premise of the covenant - faith.
This was the problem with those who had come into the churches of Galatia. They argued that the physical things of Abraham were needed if someone wanted to be justified by God. In their estimation, the Galatians needed to become Jewish converts and obey the laws of Moses before they could receive the grace of God to be declared justified and freed from their sins. Paul reminded the Galatians and these physical descendants of Abraham (of which he was one) that God had declared Abraham righteous on the sole criteria of faith. Any who would seek to join Abraham’s family, must only needs come through faith. The promise of eternal life and blessing is offered, all that is needed is faith.

Food For Thought: Explain in your own words the phrase “Abraham believed God, and it was counted to him for righteousness.”