Continuing to address the Jewish view, Paul tells them God is the God of both Jews and Gentiles. Anyone who hears the message of Jesus and accepts it is saved. He quotes Moses and Isaiah, who were two of the writers of the Old Testament, as predicting that non-Jews would listen to God’s message but that Israel would stubbornly reject it. Paul is seeing these predictions come true as most of the people coming to Jesus at this point are not Jews.
When Paul speaks of people needing to hear the message of Jesus and the need for people to take the message to them, he is speaking to those of us who know Jesus. People are far more likely to come to Jesus if we take the message to them. We should take the message to everyone, because God is the God of everyone, and anyone who trusts in Jesus will be saved!