Before ISIS, Mosul was home to 15,000 Christians. In July, Mosul was home to about 40. Any questions?

"This cultural genocide, thanks to the indifference of Europeans and many Western Christians more worried about not appearing 'Islamophobic' than defending their own brothers, [has] sadly worked," The Gatestone Institute wrote.

Mosul, the third-largest city in Iraq and home to one of the largest Christian populations in the region before the rise of, and persecution by, ISIS, now has the reputation of celebrating Christmas, minus the Christians. And yes, political correctness -- fear of calling out Islam for what it often is -- is in large part to blame.

Related: Timeline of ISIS in Iraq
Related: Attacks on Assyrians in Syria By ISIS and Other Muslim Groups

The Voice of the Martyrs lists nine major radical Islamic groups, including Al Shabab, Boko Haram, al Qaeda, the Muslim Brotherhood, ISIS and the Taliban, responsible for persecuting Christians from Afghanistan to Kenya to Libya.

And in America, it's become this, a headline from The Tennessee Star: "Miss Iraq Says Ilhan Omar Exporting 'Muslim Brotherhood Agenda' to America."

Former Miss Iraq, Sarah Idan, went on to say, during an interview on "The Sara Carter Show" that was widely reported, "Ilhan Omar does not represent me as a Muslim, does not represent millions of Muslims in the Middle East. You know, like in Arab countries, we call her the Muslim Brotherhood."

But be careful how you speak about Rep. Omar. As Jeanine Pirro learned, after her employer Fox News chastised her questioning of Omar's ability to simultaneously embrace both Islamic principles and the U.S. Constitution, too much talk can get you suspended.

Not saying Omar is a persecutor of Christians -- or in any way even anti-Christian. But the point is this: America, both overtly and subtly, has learned to tread carefully when it comes to discussing Islam-related matters.

It's very difficult to win the war without naming the enemy. It's even more difficult to win the war when the enemy's outright ignored.

"I believe the death of most people suffering today is truly because of political correctness, because the world turns a blind eye to this, and when we are politically correct, we are sympathizing with those terrorists that are destroying communities and erasing history," said Juliana Taimoorazy, the president of the Iraqi Christian Relief Council and a senior fellow of the Philos Project, during an interview in May on Fox News.

Or, another way to put it: Mosul -- from 15,000 Christians to 40.

In just a few short years.