“Not all of Abraham’s descendants
Are his children.
‘It is through Isaac
Shall be named.’”
οὐδ’ ὅτι εἰσὶν σπέρμα Ἀβραάμ, πάντες τέκνα, ἀλλ’ Ἐν Ἰσαὰκ κληθήσεταί σοι σπέρμα.
Paul said that not all (οὐδ’ ὅτι) Abraham’s seeds or descendants (σπέρμα Ἀβραάμ) are (εἰσὶν) his children (πάντες τέκνα). However, it is through Isaac (ἀλλ’ Ἐν Ἰσαὰκ) that his descendants or seeds (σοι σπέρμα) can be named (κληθήσεταί). Paul then made a distinction between the seeds or descendants of Abraham and his children. The children of Abraham came through Isaac, not his brother Ishmael. The children of Isaac are the true descendants of Abraham via Jacob or Israel as he came to be called. They are the true Israelites from Abraham via Isaac and Jacob, the twelve tribes of Israel. This citation of Paul is based on Genesis, chapter 21:12, where God said to Abraham not to be distressed but to listen to Sarah, because Isaac is where his future was, although Ishmael would have a great nation also. Paul will show off his knowledge of the Book of Genesis in these next few verses. For the gentiles, this might seem a little foreign. How familiar are you with the story of Abraham and his two sons?