If someone acts immorally - assuming some sort of free will - then they are doing so despite it being demonstrably wrong, i.e. it is a mistake as surely as 1+1=3 is a mistake. Doesn't this then give the idea of a 'bad' person a different implication - we wouldn't say the same to someone if they made a mistake in math or in their finances yet people who are simply in moral reasoning get this pejorative label. Does this then imply that as a society in our language that all humans have an innate understanding of morality to be even able to claim that they are bad not simply ignorant. Nevertheless, it seems different to say someone made an irrational decision (by inflicting gratuitous pain) and might be an irrational person than to say they are an evil one.
The difficulty I am facing is that to make an immoral decision appears like it must be ignorant and irrational, as one who fully understood right and wrong and the implications would realize they had an imperative to act differently, but this seems wholly different to our conception of evil and whether someone is evil.
Edit: I may have been a bit lax with my terms. I was saying that if one acts immorally, then either one is ignorant of morality or one is irrational, i.e. understand moral obligations but nevertheless ignore them. E.g. Selfishness.I think I have an obligation to others' well-being as much as my own, but I often spend on myself money which could be better spent on others