If Paul’s intent in verses 11-13 was not to say that God has rejected many before they were born, then what was he trying to say? What other reason might Paul have to reference Esau and the Edomites? Remember the false belief of the Israelites in Paul’s day who assumed they were going to be saved simply on the basis that they were descendants of Abraham? Paul is proving that God’s promise includes cursing those who opposed the fulfillment of that promise, even if they are of Isaac’s
