Islamic zealots are on perpetual alert for any act or expression they perceive as disrespectful of their prophet or their faith.

That sensitivity is not the issue here. The adherents of all religions are defensive of their creed. The problem with fanatical Muslims is the savagery of their response.

It is not enough to denounce critics, or to rebuke those who express disagreement with certain sacred tenets.

No, there must be blood.

The only satisfactory response is to behead, stone to death or otherwise murder the offender. No transgression, however slight, merits lesser punishment.

And any objection to this warped notion of “justice” is seen as compounding the insult to Islam.

Consider the case of Malala Yousufzai, the Pakistani girl who, since the age of 11, had publicly criticized the Taliban for its attempt to prevent girls from receiving an education.

Now 15, and widely admired for her courage, she was in a van with schoolmates earlier this month when an assassin approached and, at close range, shot Malala in the head and neck and wounded two other girls, one critically.

As outrage at the attack swelled across Pakistan, a Taliban spokesman proclaimed the shooting not merely justified by the Qur’an but obligatory for a challenge to Islamic law — women and children not exempted.

Pakistan’s army chief described the assault as driven by a “twisted ideology.” The same can be said of murderous outrages by radical Islamists in northern Nigeria, in Mali, in Myanmar, southern Thailand and elsewhere.

Let it be quickly said, however, Muslims have no corner on such wickedness.

It has been estimated that in Europe and in the American colonies during the 1600s, some 40,000 to 50,000 individuals — accused of witchcraft — were executed by drowning, hanging or public burning.

The ones who did the killing were primarily Christians.

Beginning in 1619, an estimated 645,000 human beings were plucked from their African homelands and shipped across the Atlantic to provide slave labor in Christian America.

It was Christian invaders who conquered and exploited South and Central America. It was the fledgling U.S. republic that turned its might to the dispossession and near elimination of the native North American tribes.

And it was Christian Germany that created the killing factories called concentration camps.

Unquestionably, the Taliban’s attack on a 14-year-old Pakistani schoolgirl can be described as the work of cowards and fanatics.

But throughout history, there have been countless acts of wanton inhumanity committed in the name of what professed to be religions of peace.

In short, there is shame enough to go around.