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:
They said this because of their fear of the Jews: for the Jews had come to an agreement that if any man said that Jesus was the Christ he would be put out of the Synagogue.
Who will give a decision against us? It is Christ Jesus who not only was put to death, but came again from the dead, who is now at the right hand of God, taking our part.
So it is my desire for you to be clear about this; that no one is able to say by the Spirit of God that Jesus is cursed; and no one is able to say that Jesus is Lord, but by the Holy Spirit.
Because a number of false teachers have gone out into the world, who do not give witness that Jesus Christ came in the flesh. Such a one is a false teacher and Antichrist.