From Acts of the Apostles, by William S. Kurz, SJ, commenting on Acts 10:25-26, 34-35, 44-48
Here for the first time Luke specifies that the believers who had accompanied Peter to the home of Cornelius were circumcised Jewish Christians. They were astounded that the gift of the holy Spirit should have been poured out on the Gentiles also. Gentiles were not members of God’s chosen people. Although Jews knew that Israel was called to be a “light to the nations” (Isa 49:6; see 42:6; 60:1–3), most expected that that would happen by Gentiles joining the chosen people, being circumcised, and keeping the law of Moses. Yet these uncircumcised Gentiles had obviously been filled with the Spirit of God.
The evidence from which Peter and his companions arrived at this understanding was hearing these Gentiles’ speaking in tongues and glorifying God, just as had happened to Jewish believers at Pentecost, who “were all filled with the holy Spirit and began to speak in different tongues” (Acts 2:4). The gift of the Holy Spirit is evident in its effects in the recipients, such as tongues and prophecy (see Acts 19:6), which Paul will call gifts of the Spirit (see 1 Cor 12:4–11). For the New Testament, the Holy Spirit’s coming on believers is not something imperceptible, to be accepted only on faith, but observable, sometimes even dramatic (see Gal 3:2–5; Heb 2:4). On this occasion it caused the Jewish believers who were present to expand their limited conception of God’s plan and be docile to his purposes.
Peter’s leadership is decisive in this momentous development. His response to the surprising outpouring of the Spirit on his Gentile listeners is to obey God’s obvious guidance and fully incorporate them into the Church without further ado: “Can anyone withhold the water for baptizing these people . . . ?” Because they have received the holy Spirit even as we have, what objection could anyone raise to God’s evident will to accept them fully as fellow Christians?
The Ethiopian eunuch had raised a similar question to Philip: “What is to prevent my being baptized?” (Acts 8:36). Here there would normally have been even greater resistance to baptizing a whole group of uncircumcised Gentiles. Luke makes it clear that it is God’s own direct action of giving his Spirit to these Gentiles that overrides all objections that would prohibit baptizing them. For they now have the same Spirit as the Jewish believers.
This confirms Peter’s realization that “God has shown me that I should not call any person profane or unclean” (Acts 10:28). These Gentiles too are now adopted sons and daughters of God and members of the body of Christ, God’s Son.