 The disagreement comes in what they understand God to have promised. Now the objector protests, God has promised to save me because I'm in the covenant. God has promised to save me. I'm a son of Abraham. God has promised to save me. I've been circumcised. I have the law. God has promised to save me. Even if I should be utterly faithless to God, God will be faithful to the promises that He made to Abraham and I will be saved. Let me ask you, is that what God has promised? No. That's what the Jewish objector has come to believe that God has promised. That God never promised to save all of Abraham's descendants. He certainly never promised to do so apart from faith in Jesus Christ.