How do you receive the Spirit—by works of the law or by hearing of faith?
The Spirit is received by the hearing of faith, not by works of the law. Paul asks whether the Galatians received the Spirit by law-keeping or by hearing faith, and the answer is hearing faith. Romans 10:17 confirms faith comes by hearing, and hearing involves no work, so salvation is faith plus nothing.
Les explains that in Galatians 3:2 Paul is addressing salvation and the evidence of the Spirit's reception, not the ongoing Christian experience. Paul asks if they received the Spirit by the works of the law; the answer is no way. Instead, they came to that spiritual position by the hearing of faith. Les compares this with Romans 10:17: saving faith comes by hearing, and hearing involves no work. Paul insists salvation is the finished work of Christ plus nothing; if it were otherwise, Christ died for nothing.