Sin is defined in the dictionary as "An immoral act considered to be a transgression against divine law." Since "immoral" is subjective and poorly defined, "considered" is soft and nebulous and subjective as well, and "divine law" means either nothing for some people or a variety of different things for other people, and even if you agree with a certain set of people on what "divine law" means to you within that set of people, you would still disagree on what would constitute a transgression of said divine law, any discussion of "sin" in connection with mental illness is doomed from the start.

It is not sufficiently clear that we need a whole thread on it?