Really ?He had to be. Peter didn't save him, or cause him to be saved. Peter just witnessed Cornelius and his household receive the gifts of the Holy Spirit.
Acts 11:4-14 (KJV)
4 But Peter rehearsed the matter from the beginning, and expounded it by order unto them, saying,
5 I was in the city of Joppa praying: and in a trance I saw a vision, A certain vessel descend, as it had been a great sheet, let down from heaven by four corners; and it came even to me:
6 Upon the which when I had fastened mine eyes, I considered, and saw fourfooted beasts of the earth, and wild beasts, and creeping things, and fowls of the air.
7 And I heard a voice saying unto me, Arise, Peter; slay and eat.
8 But I said, Not so, Lord: for nothing common or unclean hath at any time entered into my mouth.
9 But the voice answered me again from heaven, What God hath cleansed, that call not thou common.
10 And this was done three times: and all were drawn up again into heaven.
11 And, behold, immediately there were three men already come unto the house where I was, sent from Caesarea unto me.
12 And the Spirit bade me go with them, nothing doubting. Moreover these six brethren accompanied me, and we entered into the man's house:
13 And he shewed us how he had seen an angel in his house, which stood and said unto him, Send men to Joppa, and call for Simon, whose surname is Peter;
14 Who shall tell thee words, whereby thou and all thy house shall be saved.