The presence of God the Holy Spirit is a confirmation the someone belongs to God’s people (1 Corinthians 2:12; Acts 10:44–48). He works powerfully in the heart of God’s elect when the gospel is preached to them (Acts 13:48, Acts 13:52; Romans 5:5; Romans 10:17), authenticating salvation and serving as a guarantee that God will complete his saving work (2 Corinthians 1:22; 2 Corinthians 5:5; Ephesians 1:14).1 The Galatians received the Spirit when Paul preached to them and they believed his message (Acts 13:48, Acts 13:52).2 Before they had any chance to obey the law, they already received the Spirit and the presence of the Spirit is confirmation that they belong to the people of God (Isaiah 44:1–5; Ezekiel 36:26–27; Joel 2:28–32; Acts 2:1–47).3
2 Let me ask you only this: Did you receive the Spirit by works of the law or by hearing with faith?