Acts 10: 1-8:
Now there was a man at Caesarea named Cornelius, a centurion of what was called the Italian cohort, a devout man and one who feared God with all his household, and gave many alms to the Jewish people and prayed to God continually. About the ninth hour of the day he clearly saw in a vision an angel of God who had just come in and said to him, “Cornelius!” And fixing his gaze on him and being much alarmed, he said, “What is it, Lord?” And he said to him, “Your prayers and alms have ascended as a memorial before God. Now dispatch some men to Joppa and send for a man named Simon, who is also called Peter; he is staying with a tanner named Simon, whose house is by the sea.” When the angel who was speaking to him had left, he summoned two of his servants and a devout soldier of those who were his personal attendants, and after he had explained everything to them, he sent them to Joppa.
Cornelius was a God-fearing Gentile. He was also a Centurion which made him an officer in the Roman Army. He could have become a proselytized Jew but my guess is that he did not go though this process because he was Roman officer and soldier. He believed in the God of the Jews and that is who he exclusively worshiped. He was also quite devout in this worship.
God is about to give a lesson to the Christians and start what will be known as the Gentile controversy. It is probably good that the vision directed Cornelius to Peter. I think it will be important that Peter is involved with this issue right from the get go. That way when Saul / Paul gets involved the groundwork has already been done in some part. Truth is the only real obstacle is Peter himself and that is where God turns his attention to next.
Next: Peter’s Vision