What guidelines help nonprofits moderate comments while preserving open dialogue?

[AubreyGR]

I manage social media for a small nonprofit, and I'm struggling with how to professionally handle negative comments and heated debates on our posts about controversial community issues. Our goal is to foster discussion, but some threads devolve into personal attacks. For other community managers, what are your guidelines for moderating comments while maintaining an open forum? Where do you draw the line between robust debate and toxicity, and how do you enforce rules consistently without appearing to censor opposing views? I'm also unsure about the etiquette for engaging with critics privately versus publicly in the thread.