Somehow the Holy Spirit convinced Peter that God wanted him to accompany the messengers to Cornelius" house. [source][source][source]
". . . it is both exegetically and experientially difficult, if not impossible, to draw any sharp lines between "an angel of God [1]," the Holy Spirit [2], and the ascended Christ [3]." [4][source]
We could also add "God" ( Acts 10:28; cf. Acts 8:26; cf. Acts 8:29; cf. Acts 8:39; Acts 16:6-7; Romans 8:9-11; 2 Corinthians 3:17-18). [source][source][source]
"A God-fearer had no objection to the society of Jews, but even a moderately orthodox Jew would not willingly enter the dwelling of a Gentile, God-fearer though he were." [5][source]
Peter was to feel free to enter the house of Cornelius since the centurion was not unclean. Perhaps as Peter "was reflecting" ( Acts 10:19) he remembered Jesus" teaching in which He terminated the clean unclean distinction (cf. Acts 10:29; Mark 7:19). [source][source][source]