Acts 13:47 For so hath the Lord commanded us saying, i have set thee to be a light of the Gentiles, that thou should be for salvation unto the ends of the earth.
Paul and Barnabas had preached the gospel to the Jews in the synagogue at Antioch, but when many of them rejected eternal life they turned to the Gentiles. Many Gentile God-fearers believed and were filled with joy. That is when Paul says that the Lord called them to be a light of the Gentiles and to be for salvation to all earth people everywhere.
That is the promise for us: salvation is for everyone everywhere, and the message of salvation is to be preached to the ends of the earth. The promise says: i heard the Gospel and I believe it; therefore, i know that I am ordained to eternal life. Jesus saves me.