Should we "waste time" with people who are not interested? Should we "scatter seed" to someone clearly hostile to facts or the Truth? I think yes but I also think of this verse sometimes – Jesus talking in Matthew 10:14: "And if anyone will not receive you or listen to your words, shake off the dust from your feet when you leave that house or town." The only way I can answer these questions for me is it's case by case, and I try to obey God while ignoring my flawed self, and I leave all outcomes to Him. That last part is the most freeing for me.