“What do we mean by saying, “Salvation history? We mean the story of Our Father’s dealing with the human race. At the start, He picked one people for special help, and planned later to offer this special help to all people. We can see this from what St. Paul says Ephesians 3. 3-6. Paul says that God has revealed to him the mystery that earlier times had not known. It was this: not only the Jews, but the gentiles too are called to be part of the people of God!
But even before Christ came, Our Father did provide for the gentiles, who were not among the chosen people. St. Paul reasons this way in Romans 3. 29: “Is He the God of the Jews only? Is He not the God also of the gentiles?” St. Paul means that if God did not take care for the salvation of all, He would act as though He were the God of the Jews only. But, St. Paul insists, He did take care for all. He did this through faith. He did this even for those who had never heard of the future coming of Christ.
We can see this from what St. Paul tells us in Romans 2. 14-16. There Paul says that Spirit of God, who is of course the same as the Spirit of Christ, writes His law in the hearts of all. Those who accept that law, may not know that what they are accepting is the Spirit of Christ. Still, they really accept that Spirit of Christ, if they do what He tells them in their hearts to do. So they have what we could all an implicit faith. So, because they accept the Spirit of Christ — without knowing that that is what they are doing — they can even be called Christians. For St. Justin the Martyr, around 150 A.D., in his First Apology (46) said that many in the past who even might have seemed to be atheists, were really Christians, because they followed the Divine Word. That is what we have just described. St. Augustine wrote about this, in his Retractations (1. 13. 3) where he answered the pagan Celsus. Celsus said it seemed as though God took no care of people in past times. St. Augustine said: “This very thing which is now called the Christian religion existed before. It was not absent from the beginning of the human race, until Christ Himself came in the flesh, and then the true religion, that already existed, began to be called Christian.” Scientists don’t agree on how old the human race is. But in 1983 Allan Wilson of the University of California, Berkeley, wrote that all the human there are today descended from one mother, who lived 350,000 years ago (Science News, August 13, 1983). Many scientists today think Wilson is right, but they now say the mother lived 200,000 years ago (Newsweek, Jan 11, 1988).” – William G. Most, EWTN