Paul is in anguish for his fellow Israelites. Even though they had all the blessings and privileges of receiving God’s revelation in the Old Testament, they did not have faith in Christ. There are scores of God’s promises in the OT for the Israelites.
God’s promises were never based upon physical descent nor our own works. Right from the beginning, it has always been God’s own sovereign grace towards those that he chose. God is God and he will have mercy on whom he will have mercy. Our salvation is based entirely on God’s electing grace upon us. That does not mean that God is unjust – we are all sinful, deserving only God’s wrath (as Paul mentioned in 1:18 onwards). God would have been completely just in leaving us in our sins but yet in his sheer grace, he has elected some to be saved. That is why the golden chain of salvation is an unbreakable chain, because right from the start to the end, it is God and God alone who saved us.
