It's better to debate them on their choices so they can find their own way towards a more enlightened and equitable worldview.
I've also come to realize that this may partially explain why conservatives I know have been reluctant to engage in political discussion in these times. They're being backed into having to defend fundamentally indefensible positions.
Rather than forcing them to opt out, maybe it would be more productive to provide them an avenue out by engaging them in a more positive way. I'm still trying to figure out what that is, however.