Re: "... promoting diversity."
You may have more luck by explaining it in their language. The key concept is "intersectionality," which explains that people are privileged and/or unprivileged for various reasons, which may intersect in any individual.
In other words, you might be privileged for being white while being unprivileged for having the wrong social background. Or disability, or health issues, or politics, or whatever.
It's a powerful idea, not least because it prevents the very "white is always wrong" scenario you describe.
Biting the hand that feeds IT
