Khizr Khan and his wife Ghazala are Gold Star parents, and worthy of our gratitude, comfort and admiration. They have, however, also placed their son’s heroic death in the political arena, in the service of Hillary Clinton’s presidential ambitions.

Therefore, while it may be unwise for Donald Trump to criticize them, they are not beyond criticism.

In fact, their public statements repeat several lies the left has perpetuated to crush opposing views, which must be exposed.

1. Terror has “nothing to do with Islam.” That statement, made by Mr. Khan to CNN on Sunday, is simply ridiculous. It also happens to be the stated policy position of the Obama administration and Hillary Clinton’s campaign. The left clings to this belief because it is not prepared to confront the ongoing terror threat, or to admit the failure of its multiculturalist policies. That cognitive dissonance persists even among those who are terror’s victims.

2. Conservatives oppose all immigration. Mr. Khan told the Democratic National Convention: “If it was up to Donald Trump, [my son] never would have been in America.” The Khan family came to America in 1980, when Islamic terrorists had barely begun to attack the U.S. Trump has presented different versions of his proposal, but the basic thrust is to allow legal immigration while limiting it from terror-prone countries. The Khan family would have been welcome.

3. War is never the answer. That claim was not made by Khan himself, but was implicit in the audience’s reaction inside the Wells Fargo Arena. While they applauded the Khans, left-wing, anti-war delegates heckled the military speakers that followed, including a wounded veteran. Happy to honor a dead veteran, whose sacrifice might suggest the futility of war, they were rude to living ones. The left rejects war, period — though weakness has always invited aggression.

4. The Constitution doesn’t mean what it says. The left likes to reinterpret the text for its own purposes. Thus Mr. Khan held a pocket Constitution aloft, and mocked Trump’s immigration policy: “Have you even read the U.S. Constitution? I will gladly lend you my copy. In this document, look for the words ‘liberty’ and ‘equal protection of law.’” The latter phrase only applies to citizens, not immigrants. Trump’s policy might be inadvisable, but it is constitutional.

5. The media have no liberal bias. When Patricia Smith, the bereaved mother of Benghazi hero Sean Smith, spoke at the Republican National Convention, she received 70 seconds of network coverage. Mr. Khan and his wife have enjoyed 50 times more attention, according to an analysis by NewsBusters, as they continue an extensive circuit of sympathetic interviews and TV appearances. The left pretends the media are not biased, but the numbers tell the truth.

And the core truth, which Mr. Khan and his friends in the media wish to suppress, is that radical Islam is directly responsible for brutal terrorism that threatens Americans and innocent people around the world.

Rather than question Ghazala Khan’s silence onstage, Trump would have done better to insist that he will be the best president American Muslims have ever had, since only he will prevent militant infiltrators from recruiting American Muslim youth to their cause.

From a conservative perspective, it has been disheartening to see Donald Trump struggle to react appropriately to a speech that, while powerfully emotive, was based on false premises.

There is a silver lining, however. Perhaps more American Muslims will be motivated to serve by the Khan family’s example.

And perhaps some of Khan’s new liberal fans, having rushed to buy copies of the pocket Constitution he held onstage, might actually try reading it properly for once.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. His new book, See No Evil: 19 Hard Truths the Left Can’t Handle is available from Regnery through Amazon. Follow him on Twitter at @joelpollak.