I’d say something along the lines of, “when your ‘opinion’ upholds the mistreatment and oppression of others, that’s not an opinion, that’s bigotry. i’m not going to stand for or respect bigotry of any kind just because you aren’t willing to acknowledge why it’s unacceptable.”
remember: if your “opinion” disrespects the existence of a marginalized group, it’s not your opinion, it’s a fundamental flaw in your character!!