Political correctness has become one of the constants of our age. Many of the examples are more ridiculous than anything else.

Inappropriate Halloween costumes, campus safe zones free from controversial ideas, saying “happy holidays,” and now, from Sweden, men sitting when they have to urinate. But at a time when people are being murdered at home and abroad because of their religion, PC — which really stands for political cowardice — can be downright dangerous.

The latest case just occurred in Philadelphia. Thirty-year-old Edward Archer ambushed a cop, wounding him three times. The officer should recover, but he and we can be thankful that Archer, who blasted away 11 times, was such a bad shot.

The attacker, dressed in what one cop termed “Muslim garb,” was quite explicit about why he shot Officer Jesse Hartnett. Said Police Commissioner Richard Ross, Archer “has confessed to committing this cowardly acting the name of Islam.” Why? “According to him, the police defend laws that he believes are contrary to Islam.”

Captain James Clark, head of the city’s homicide unit, added more detail: Archer “stated that he pledges his allegiance to Islamic State, he follows Allah, and that this is the reason he was called upon to do this.” There was no standard claim of an underprivileged background or other form of victimization. Archer stated “I follow Allah and I pledge allegiance to the Islamic State. That is the reason why I did what I did.” Explained Clark: “He just kept on echoing those sentiments, and he wouldn’t give us anything more than that.”

Sounds like a terrorist attack to me. Probably not orchestrated by ISIS. After all, who would want an incompetent like Archer as a foot soldier? But his attack, like that in San Bernardino, demonstrates how the terrorist threat in America is shifting from conspiracies organized overseas to incidents developed at home.

These assaults tend to be much smaller than 9/11, but still can cause tragic death and harm. Thankfully Officer Hartnett had a gun, unlike any of the San Bernardino victims.

Obviously, it hurts all of us to find that someone in our own community would commit such a vicious crime. But then, one has to ask why people murder for any reason. It’s important to know why people act as they do in order to better prevent the next crime. That’s certainly the case with terrorism.

However, it turns out that those in authority in the City of Brotherly Love prefer to stick their heads in the sand. At least Mayor Jim Kenney does, anyway. (It is his preferred modus operandi: upon taking office he declared Philadelphia to be a “sanctuary city” opposed to federal immigration laws.)

Kenney said the shooting is “terrible and it does not represent this religion [Islam] in any way shape or form or any of its teachings.” The incident, he added, “has nothing to do with being a Muslim or following the Islamic faith.”

Uh, has nothing to do with Islam? Makes you wonder how much clearer Archer would have had to be before the mayor would take him at his word!

Of course, most Muslims in America don’t believe such horrid things and would never commit such a crime. In their view, Islam does not require murder.

But obviously Archer does. Just like those who killed in San Bernardino. And in Paris. And in so many other places around the world.

Nothing is gained by attempting to deny the obvious. Who better knows what motivated the terrorist: the terrorist or the city’s liberal mayor? As long as Islam moves even a few people, like Archer, to kill, we have a major problem. The solution isn’t obvious, but we should start by recognizing that we face a religious challenge.

Of course, it isn’t politically correct to say that. Everyone is supposed to repeat the mantra that Islam is a religion of peace. But that wasn’t the case for Richard Archer and many before him. Failing to understand and acknowledge the obvious isn’t just politically cowardly. It’s dangerous and will cost lives.

We’re involved in a war. Our enemy is a motley but deadly mix of Islamic extremists. Unfortunately, some of them live among us. It is time our political leaders, including mayors and especially the president, stated the obvious.

It’s always easy to joke about political correctness. But the Philadelphia shooting should remind us that accepting PC nonsense risks more than our liberty. Not resisting PC also could cost us our lives.