I don't believe mental illness is caused by character flaws. I don't know anyone who doesn't have character flaws. I don't think there is anyone who doesn't have character flaws.
I would question the character of anyone who would say mentally ill people are losers and deserve what they get.
I'm curious about why you question your morals so much. I don't think a bad person would question their morals. Do you feel like you don't pay enough attention to others or don't try to get along with others? That is something that is within your control to a great extent.
Being agnostic I probably shouldn't comment on the cursed by god possibility but I think it's highly unlikely that you are