Amen..it is a deceptive doctrine that can ship-wrecked believers. The thing is - there is an element of truth in it but it is being "mis-applied" and thus they believe they can never sin in the flesh again.
In reality as we have seen - they do the works of the flesh quite a bit. In their minds they don't do any sinning anymore because they don't smoke, drink, swear, commit adultery but they don't mention all the other works of the flesh. Like "hypocrisy, slander, malice, strife causing..etc"