Romans 4

“For the promise to Abraham and his offspring that he would be heir of the world did not come through the law but through the righteousness of faith” (v13).  A common misunderstanding is that in the Old Testament, people were saved by obedience to the law, and now, we are saved by faith in Christ.  Yet Paul explains that no one was ever saved by the law; Abraham was justified by faith in God, and he received the promises of God long before he was obedient to a command (v3,9-10).  

We are Abraham’s spiritual children (v11) when we are “fully convinced” that God is able to do what He has promised (v21).