Because, if you say with your mouth that Jesus is Lord, and have faith in your heart that God has made him come back from the dead, you will have salvation:
Being conscious that a man does not get righteousness by the works of the law, but through faith in Jesus Christ, we had faith in Christ Jesus, so that we might get righteousness by faith in Christ, and not by the works of the law: because by the works of the law will no flesh get righteousness.
And be seen in him, not having my righteousness which is of the law, but that which is through faith in Christ, the righteousness which is of God by faith:
I have knowledge that your living-place is where Satan has his seat: and you are true to my name, and were not turned away from your faith in me, even in the days of Antipas, my true witness, who was put to death among you, where Satan has his place.