I think the intrinsic and chemical properties of weed are totally irrelevant. Whether God intended THC to be in the body or not is irrelevant (after all, nothing in the body would exist if it weren't for the body's necessity to absorb foreign substances and assimilate them into tissue and energy and blood, etc.)

What is relevant is a given person's security and comfort with their own sober self (nothing conciously psychoactive in the body). If a person gets high to become desensitized to real-self emotions, or to feel more normal about his or her self, that would qualify as abuse.

Everyone gets angry or sad or frustrated, but too many of us use negative emotions as a justification for getting high in some way, and by doing so they totally numb the sequence of emotions that lead the person through character evolution up to the higher ground of having felt the full burden of one's emotions.They cheat themselves out of emotional growth, and become emotionally stunted. This is why you see 28 year olds who think and act pretty much like they are fifteen. That age is roughly when these self-destructive habits begin, and it's easy, so you keep doing it. It these people that give stoners a bad rep.

It could have been weed alone that stunted emotional growth, but normally there's additional substances.

The person who smokes weed responsibly is the person who smokes it when nothing is troubling him emotionally and he considers himself in a normal happy state beforehand.