[Roodgorf]

The thing is, I don't think the "What would it take to convince you?" discussion is generally actually fruitful for beliefs like these. For example, Bill Nye posed this exact question to Ken Ham during their Evolution/Creationism debate and essentially his response was "Nothing, this is my belief and I'm sticking to it."

So, it seems like your best option is just to ignore those with decidedly unscientific opinions for the moment and attempt to instill more genuinely curious/less dogmatic thinking into those who have not already made up their minds.