The Lord had said to Abram, “Leave your native country, your relatives, and your father’s family, and go to the land that I will show you. I will make you into a great nation. I will bless you and make you famous, and you will be a blessing to others. I will bless those who bless you and curse those who treat you with contempt. All the families on earth will be blessed through you.” – Genesis 12:1-3
This promise for universal blessing to the “families” of the earth is essentially repeated many more times in Genesis.
In Genesis 12:3 and 28:14 the Hebrew phrase for “all the families” (kol mishpahot) is rendered in the Greek Old Testament by pasai hai phulai. The word phulai means “tribes” in most contexts. But mishpahot can be, and usually is, smaller than a tribe, more like a family which is part of a tribe such as Achan’s story in Joshua’s defeat at Ai.
There other three are found in Genesis 18:18, 22:18 and 26:4 and they all use the phrase “all the nations” (Hebrew: kol goyey) which the Septuagint translates with the familiar panta ta ethne in each case. this again suggests strongly that the term panta ta ethne in missionary contexts has the ring of people groups and not Gentile individuals.
The New Testament explicitly cites this particular Abrahamic promise twice.
You are the children of those prophets, and you are included in the covenant God promised to your ancestors. For God said to Abraham, ‘Through your descendants all the families on earth will be blessed.’ – Acts 3:25
In the same way, “Abraham believed God, and God counted him as righteous because of his faith.” The real children of Abraham, then, are those who put their faith in God.
What’s more, the Scriptures looked forward to this time when God would declare the Gentiles to be righteous because of their faith. God proclaimed this good news to Abraham long ago when he said, “All nations will be blessed through you.” – Galatians 3:6-8
What we may conclude from the wording of Genesis 12:3 and its use in the New Testament is that God’s purpose for the world is that the blessing of Abraham, namely, the salvation achieved through Jesus Christ, the seed of Abraham, would reach to all the ethnic people groups of the world. This would happen as people in each group put their faith in Christ and thus become — sons of Abraham — and heirs of the promise. This event of personal salvation as persons trust Christ will happen among “all the nations.”