One of the great things about Romans is the number of times Paul takes a concept - often from the history or traditions of Israel - and turns it on its head, Copernicus style. And after he's "done a Copernicus" to the concept, it is almost impossible to think about it any other way but the new way.
In our studies of chapters 9-11 last week we came across one of these beautiful moments.
In the history of Israel, being a descendent of Abraham is one of the key concepts. To be in the line of Abraham means you are in the line of God's promises, you can look forward to his blessings and the great inheritance that awaits his people. The Israelites were very proud of their "bloodline" and the benefits that "being in the family" brought.
But look at what Paul does with this.
"For not all who are descended from Israel belong to Israel, and not all are children of Abraham because they are his offspring, but "Through Isaac shall your offspring be named." This means that it is not the children of the flesh who are the children of God, but the children of the promise are counted as offspring." (Rom 9:6-8 ESV)
See how he turns the definition of "descendent" on its head? The thing that matters is not your "flesh" line, but your "promise" line.
He then goes on demonstrate the existence and importance of this re-definition by using two examples from Israel's history.
First - Abraham himself. In verse 9 Paul quotes Genesis 18, when God visits Abraham and Sarai and promises that this time next year they will have a son, the son who will carry on their name, despite their advanced years. The key fact is that at this point in Abraham's life, he already has a son, Ishmael. In "bloodline" thinking, the descendent exists because Abraham has taken things into his own hands and had a son with his servant. But that son is not the son of the promise. Isaac is yet to be born. Promise "trumps" bloodline.
Second - Jacob and Esau (v10-12). Perhaps the most famous demonstration of God's electing power. Twins, whose birth order defines their "bloodline" standing, and yet, the divine promise reverses the order. Instead of the younger serving the older as would be expected, the older serves the younger. The promise of God again trumps the bloodline.
So what's the point of all this?
To make it clear that it is not your mum, your dad or your family heritage that saves you. It is your inclusion in the promises of God. And Romans makes it abundantly clear that this inclusion is achieved through faith in the saving work of Christ - which in fact is not an achievement of ours, but of God.