Of all the outrages to decency and common sense during National Rifle Association president Wayne LaPierre’s bizarre press conference following the Sandy Hook Elementary School massacre, the most offensive may have been his depiction of America as a dark hell haunted by homicidal maniacs.

“The truth,” LaPierre insisted, “is that our society is populated by an unknown number of genuine monsters — people so deranged, so evil, so possessed by voices and driven by demons that no sane person can possibly ever comprehend them. They walk among us every day. And does anybody really believe that the next Adam Lanza isn’t planning his attack on a school he’s already identified at this very moment?”

Monsters, evil, possessed. Demons, for the love of God.

Is this the 21st century, or the 17th? For LaPierre, as for many adepts of the gun cult, it follows that every grown man and woman must equip themselves with an AR-15 semi-automatic killing machine with a 30-round banana clip to keep monsters out of elementary schools. “Die Hard: With a Blackboard.”

To be fair, polls show that most gun owners support reasonable reforms like closing the “gun show” loophole that currently allows no-questions-asked sales that evade FBI background checks. It may be politically possible to ban high-capacity magazines and to reinstate something like the assault weapons ban allowed to expire in 2004 — yet another of President George W. Bush’s many gifts to the nation.

That these actions would have limited short-term effect is no reason not to act. Nobody’s Second Amendment rights would be compromised either. America can’t achieve sensible gun laws without first politically isolating extremists.

But there’s another way that LaPierre’s appalling rhetoric helps make a bad situation worse. Loose talk about possession and demons serves only to deepen the stigma and shame surrounding mental illness and contributes to society’s refusal to deal seriously with its effects.

Newtown mass shooter Adam Lanza hasn’t been, and probably can’t be, diagnosed with any certainty. But all the signs point to paranoid schizophrenia, a devastating brain disease whose victims are no more possessed by demons than are cancer patients or heart attack survivors.

Psychiatrist Paul Steinberg writes that early signs of the disease “may include being a quirky loner — often mistaken for Asperger’s syndrome,” the less stigmatizing diagnosis Nancy Lanza reportedly told friends accounted for her son’s peculiarities.

Schizophrenia is a physiological disorder of the prefrontal cortex of the brain, resulting in disordered and obsessive thinking, auditory hallucinations and other forms of psychosis. Sufferers often imagine themselves to have a special connection with God or some other powerful figure. It’s when they start hearing command voices telling them to avenge themselves upon imagined enemies that terrible things can happen.

Ronald Reagan’s would-be assassin John Hinckley Jr. suffers from schizophrenia; the same also goes for John Lennon’s killer Mark David Chapman. More to the point, rampage shooter Seung-Hui Cho, who killed 32 students and teachers at Virginia Tech in 2007, had been in and out of treatment for paranoid schizophrenia, but never hospitalized for long enough to bring him back to reality.

Nobody knew what to do about Jared L. Loughner, who killed six people while attempting to murder Rep. Gabby Giffords in Tucson. Same disease. After James Holmes began showing signs of advancing psychosis, University of Colorado officials more or less, well, “washed their hands of him” would be a judgmental way to put it. Then he killed 24 strangers attending a Batman movie in Aurora, Colo. He reportedly mailed a notebook describing his mad plans to a university psychiatrist, which she received only after the fact.

With the possible exception of Lanza, all of these killers had exhibited overt symptoms of psychosis previous to their explosive criminal acts. They belonged in lock-down psychiatric hospitals under medical treatment — whether voluntarily or not. Nobody in Seung-Hui Cho or James Holmes’ state of mind can meaningfully decide these things for themselves.

Properly speaking, psychosis has no rights.

Yet the biggest reason people don’t act is that for practical purposes, ill-considered laws make involuntary commitment somewhere between difficult and impossible. Sources told New York Times columnist Joe Nocera that Connecticut makes it so hard to get somebody committed to a psychiatric hospital against their will that Nancy Lanza probably couldn’t have done anything had she tried. (And risked antagonizing her son in the process.)

“The state and federal rules around mental illness,” Nocera writes, “are built upon a delusion: that the sickest among us should always be in control of their own treatment, and that deinstitutionalization is the more humane route.”

A liberal delusion, mainly. The good news is that anti-psychotic medications work; diseased minds can be treated. Putting somebody into a psychiatric ward for 30 days shouldn’t be as simple as a 911 call, but neither should it require the near equivalent of a criminal trial.

Just as with gun control, lives hang in the balance.

(Gene Lyons canbe reached by email at eugenelyons2@yahoo.com)