In what way should believers serve?
Believers should serve in newness of spirit, not in the oldness of the letter. Having been delivered from the Law, which was an administration of death, they now serve in the spiritual realm through the transformation of life, not by legalistic adherence to the letter of the Law.
Les explains that because believers are delivered from the Law—an administration of death—they are no longer held by it. Instead, they serve in newness of spirit, not in the oldness of the letter. This means the whole transformation of life is in the spiritual realm, not in legalistic adherence. Les warns that the flesh wants legalism, a law, but the believer is to believe the Gospel and not move into a deeper spiritual life by the flesh, as Galatians 3:3-5 addresses.