Mental illness doesn’t make people racist. It can make their already racist tendencies and thoughts worse.
Let me clarify, there are some mental illnesses which lower inhibitions, causes or increases paranoia, etc… Let’s use my bipolar disorder as an example. Medicated, I’m a relatively calm person who can stop herself from buying a $200 relay necklace. Not medicated and with access to money? I’d probably have two of those. And an N7 hoodie. Maybe a Dorian plushie too.
The medication is like that wall that prevents people from doing ridiculous shit they think about. It stops us from doing things that are mostly harmless to others, but do great harm to ourselves and sometimes out bank accounts.
That’s the thing about mental illness. We’re mostly a danger to ourselves. The stuff we’re likely to do will, nine times out of ten, hurt us more than it hurts anyone else. Racist mentally ill people are just more likely, when untreated, to loudly make it known they’re racist. They’ll still think a Black person is a nigger, but they’re less likely to say it when treated.
There are “normal” people who do the same thing. For them, it may take other substances (like alcohol) to lower their inhibitions and expose what was already there.
I say all that to say this, if you’re racist, you’re racist. Mentally ill or not, that racism will still be there. Saying “racism is a mental illness” is a cop out that stigmatizes mental illness. What you’re trying to do is separate all the racist people into their own little group so you can pretend you’re not one of them. There are plenty of “normal” people who say and do messed up stuff and y’all need to own that.