To call someone a heretic is to bring a very serious charge against them. The word is often thrown around amongst Christian groups seemingly without an understanding as to what they are actually saying about someone when they call them a “heretic.”
The phrase, “The spirit is willing, but the flesh is weak” is, I think commonly understood to mean that someone wants to do something but is unable to due to physical limitations. However, I think there is more to the phrase than denoting mere physical inability.
