The Apostle Paul made the statement above because the Gentiles were considered Heathens, by the Jews. The Jews were the ones chosen of God; hence, they saw the rest of the world as unclean. When the Lord Jesus came, He came as a Jew and picked His apostles from among the Jews. After He left, and sent out these apostles as ministers, they ministered only to the Jews, the chosen people of God.
For I speak to you Gentiles, inasmuch as I am the apostle of the Gentiles, I magnify my office (Romans 11:13).
Subsequently, God opened the door for the Gentiles to receive the Gospel and sent Peter to the house of Cornelius, a Roman Centurion. Peter ministered the Gospel to Cornelius and his household, and the Holy Ghost came on all of them, to the astonishment of the Jewish believers that accompanied Peter.

