One obvious retort to the Second amendment absolutists is that the first three words are 'A Well regulated...'. Thus it is spelled out explicitly that the Federal government has the power to regulate firearms. Under Casey anything short of a ban is an acceptable regulation. Pointing out the more sophisticated, nuanced explanations that mental health professionals use does not divide people into the Good and the Bad. Calvinism posits an elect. There seems to be a need among a certain cohort to have simple, defined answers to complex problems. There is also a need to feel superior to others. If you 'get guns into the hands of good people' ( who the one speaking always assumes they are part of) we will be able to just look at their hat color to see if they are part of the elect. So we have a combination of a fetish for firearms mixed with a need for certianty. Nothing could possibly be wrong with that?