Is salvation by faith alone or faith plus works?
Salvation is by faith plus nothing, not by faith plus works. Paul teaches that the Spirit and the evidence of salvation are received by the hearing of faith, not by the works of the law. If salvation were by works, Christ died in vain. Saving faith is the kind that needs nothing else.
Les explains that Paul's phrase "faith plus nothing" applies specifically to salvation, not to the Christian experience as we go on down the road. He contrasts the finished work of Christ with adding works of the law, saying that if it were otherwise, Christ died for nothing, or in vain. In the chapter 3 passage, Paul asks whether they received the Spirit by the works of the law or by the hearing of faith, and the implied answer is no way to law-keeping. Les cross-references Romans 10:17, where faith comes by hearing, and notes there is no work in hearing.
O foolish Galatians, who hath bewitched you, that ye should not obey the truth, before whose eyes Jesus Christ hath been evidently set forth, crucified among you?