A colleague used to say there was nothing like being attacked to bring Americans together. He said we had always been able to set aside our disagreements in wartime to face a common enemy. He wished we could muster up that same sense of resolve and community in peace time.

Maybe it’s the changing nature of war — now often carried out as terrorist attacks — or the changing face of the victims and the attackers. Maybe it’s the changing face of the population, for that matter. But it’s hard these days to find that sense of common community after an attack. We can’t agree on who or what the enemy is. We can’t even agree that those attacked were part of the family of Americans. These days, in the face of a tragedy, our instinct is to turn on one another.

And so it was after Sunday’s mass killing at an Orlando gay bar. People quickly lined up on sides, with different narratives of what had happened and why.

The problem is, some degree of suspicion is justified. The anti-gay rhetoric across the country has been deafening. Same-sex marriage and a presidential directive on transgender bathroom use in schools became rallying cries this presidential primary season. Preachers, candidates and surrogates, Bible-thumping talk-radio hosts and political strategists alike have built campaigns on demonizing gay people. Yet to hear Donald Trump’s take on Sunday’s killings, Omar Mateen’s homophobia was the result of “radical Islam.”

The presumptive Republican nominee for president used the occasion to repeat his call for foreign Muslims to be banned from America. While it’s nice to hear him supporting LGBT people, he has previously been silent in the face of some anti-gay rhetoric, even promising to appoint a Supreme Court justice who would help dismantle marriage equality.

The fact is, a ban on Muslims wouldn’t have prevented Mateen, an American-born U.S. citizen, from being here. It would have kept out his Afghan-born parents before he was born.

Trump even suggested subtly that President Barack Obama doesn’t really want to stop jihadism. “He doesn’t get it, or he gets it better than anyone understands,” he warned. He accused Democratic rival Hillary Clinton of supporting “policies that bring the threat of radical Islam into America.”

Clinton had a different take-away, which I share: Trump’s anti-Muslim positions are damaging efforts to defeat terrorism. When he or any other American leader makes all Muslims guilty by association with their religion, it’s heard by all Muslims, including those who weren’t radicalized before. And it feeds the perception the U.S. is at war with Islam itself.

Mateen reportedly found his way to extremist groups and ideologies with the help of the internet. He called the Boston Marathon bombers his “homeboys,” and funneled whatever rage and personal demons he had into a narrative of grievance as a Muslim. But Mateen also hated black people. He assaulted his Muslim ex-wife. If only we could isolate one culprit like “radical Islam,” and go to war with it. But going strictly after Islamists also wouldn’t cover homegrown white Christian mass killers.

The president called the shootings both a terrorism issue and a gun control issue. It is also a bias issue, and each of those contributors has to be dealt with separately. But dealing with just one of them right away could hamper the ability of angry, hateful or deranged killers to carry out mass shootings like those perpetrated by gunmen like Mateen and Roof and Lanza, Dylan Klebold, Syed Farook, Tashfeen Malik, Christopher Harper-Mercer and Elliot Rodger. We could take away their easy access to weapons.

There’s your common enemy: Weapons of mass destruction. There is no defensible reason for an ordinary citizen to be able to buy an assault weapon. And there’s your fix: Re-institute an assault weapons ban and implement comprehensive background checks for all gun sales, to keep them away from mentally unstable people and anyone who ever appeared on a terror watch list.

Let’s work toward a day when a racist attack on a black church, a sermon demonizing gay people and even a public Koran-burning are considered an attack on all of us and on the values we share. But first, let’s honor Sunday’s victims by making it hard for would-be killers, whatever their twisted motivation, to act on those impulses.

Rekha Basu is a columnist for the Des Moines Register.