How do we 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. Faith comes by hearing and believing God's Word: that Christ died and rose again. Hearing involves no work; it is taking God at His Word, and on that basis God moves in and does what needs to be done.
Les explains that receiving the Spirit is not by the works of the Law but by the hearing of faith. Hearing is not a work; faith comes by hearing, as we contemplate and recognize that Christ died and rose again, and believe it. By believing, we listen to the Word of God. Faith is taking God at His Word: God said it, we believe it, and God recognizes it. On that basis, He moves in and does everything that needs to be done. Scripture says it is by faith, not the works of the Law. In verse 3, having begun in the Spirit, they are not made perfect by the flesh. The flesh refers to the Law, which was fleshly, weak, and beggarly. So the Spirit is received by the hearing of faith.