Why does the flesh want legalism?
Legalism appeals to the flesh because the desire to be under some kind of law is part of the old Adamic nature. Scripture contrasts serving in newness of spirit with the oldness of the letter, yet the flesh still gravitates toward law and legalism.
Les teaches from Galatians 3:3 that the Galatians had begun in the Spirit by Paul's Gospel through faith plus nothing. Paul then asks whether they were now going to move into a deeper spiritual life by the flesh. Les explains that what the flesh wants in the Galatian churches is legalism—Law. He says it is just part of the old Adamic nature to want to be under some kind of a Law. By contrast, believers are delivered from the Law, which was an administration of death, so they should serve in newness of spirit, not in the oldness of the letter. The way into that spiritual frame of thinking is to believe the Gospel.
Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?