The phrase all those who are far off
echoes language found in Isaiah 57:19 and is a reference either to Gentiles (see Acts 22:21; Ephesians 2:13, Ephesians 2:17)1 or to diaspora Jews living far away from Jerusalem (see Acts 2:9–11). Given what we learn in Acts 10:1–48, it is likely that Peter only has diaspora Jews in view at this time2 even if the language he uses includes Gentiles.
39 For the promise is for you and for your children and for all who are far off, everyone whom the Lord our God calls to himself.”