God looked ahead and saw the corruption that would befall mankind. Each generation gets more wicked and more evil. Even among Israel, sin's stronghold grew and they turned away from God every chance they got. Isaiah spoke that unless God left them descendants they would have faired like Sodom and Gomorrah and be completely destroy by that corruption. Fortunately for us, we are the descendants that Isaiah spoke about. The true children of God are born again believers who have put their trust in Jesus as their savior. God was not satisfied in letting His descents struggle under the power of sin any longer. So he provided a way for his children to be living children, born again with His spirit sustaining life on the inside. This can only be accomplished through Christ Jesus.
This is an amazing truth, because Paul has been teaching that not all of Israel is truly of the promise spoken to Abraham, only those who are born out of faith belong to it ( Romans 9:8 ). This was the way God provided for us to escape from the corruption in the world. He has given everyone a choice, even the natural line of Abraham which is the nation of Israel. They too have to come into faith and trust in Jesus as their savior, not relying on the Law of Moses and their works to accomplish their justification. Paul is quoting from Isaiah when he said that only the remnant will be saved. "Though your people, O Israel, be like the sand by the sea, only a remnant will return. Destruction has been decreed, The Lord, the LORD Almighty, will carry out the destruction decreed upon the whole land" ( Isaiah 10:22-23 ). Although they number as great as the sands of the sea only a small number will be saved from perdition. This is a sobering realization, especially since the Jews have a wonderful heritage. However, God calls us by name and has chosen us to be his children. It is a matter of the heart and not a matter of belonging to a natural line. He calls and invites and we have to respond in faith, nothing more and nothing less.
Right now this call is open but eventually God will conclude his accounts with men completely. At that time, the only thing that will matter is what we have done with Jesus. Do we accept him as our savior and our propitiation for sin? Or do we reject him and rely on our own works to obtain reconciliation with God. Paul is pleading grace with his own people even though most have rejected Jesus. Isaiah prophesied it and Paul is reminding this nation that Jesus is the only way. We too have to accept this message and understand this grace. Once we do this, we are counted among the true children of Israel, God's chosen people on earth through faith in Jesus' atoning blood. We are the descendants that Isaiah looked forward to so that God's people would survive and flourish on the earth.
Today, if you believe in Jesus you have been joined to the remnant of Jews that have been saved. God has called for himself a people that were previously not a people and has called us beloved where previously we were not loved ( Romans 9:24-26 ). All of this is by his grace. Today, it is my prayer that you understand this grace and let it be the foundation of every truth that God leads you into, amen.