What does Galatians 3:5 mean?
Paul is asking the Christians in the region of Galatia a series of leading questions. Apparently, some of them have started to believe false teachers who are insisting that even those who trust in Christ must follow the law to be truly saved. Paul wants to help his readers to see how foolish that idea is (Galatians 3:1).Now he asks them about the undeniable supernatural things they have seen the Holy Spirit do, including miracles. The earliest Christians often received God's Spirit with some display of God's power, such as the sudden ability to speak in languages they didn't know. In many cases, more miracles followed, including supernatural healings. That happened in Galatia (Acts 14:3, 8–11).
Paul repeats his question from Galatians 3:2. Did God give them His Spirit and display His power by works of the law? Or did He do so in response to their hearing the truth and receiving it with faith? It should not be a hard question. After all, the Galatians had not yet done any works of the law when God sent His Spirit to them. The Spirit had come immediately after they had believed and before they could "do" anything.