We have Paul's apostleship, Paul's authority now who was Paul's audience?
Romans 1:6-7 (NASB) " among whom you also are the called of Jesus Christ;
to all who are beloved of God in Rome, called as saints: Grace to you and peace from God our Father and the Lord Jesus Christ. "
Look at Their Calling: Called of Jesus Christ
Their Connection: Beloved of God
Their Commission: Called Saints( to be set apart)
Their City: Rome
Their Charter: Grace followed by Peace
This is who Paul was writing to.