Some people cannot be reached. Don't try.
However, having conversations with them, you being rational, they being emotional, you citing facts, they denying them, within earshot of others, helps build your rational case and dismisses their irrational POV. Rarely is the person to whom you are speaking (or writing) the actual target of your efforts. It is those quiet bystanders whom you are trying to win over.
Keep the faith and don't worry about closed minds. Just use them as foils.