As horrors from the streets of Tehran snake-danced past America’s eyes the other night, I had an eerie TV experience: viewing comparably unconscionable ugliness on the streets of America.

It came from the 2007 documentary Chicago 10 — footage from the bloody riots during the 1968 Democratic National Convention.

Chicago 10 is pulsing evidence that even in a republic whose plans are best-laid, authority can overreach in horrific fashion.

Also on my mind at the same time was a commentary on Salon.com about the perils of unchecked power. The commentary’s inspiration is Iran, but you can certainly see a lot about America between the lines.

“The demise of political racism leaves political religion standing as the most widespread form of tyranny in the world,” Michael Lind writes.

He’s talking about mullahs and clerics and a nation that calls itself democratic but is nothing of the sort.

It’s some democracy, for instance, when candidates must seek the approval of the clerics of Iran’s Guardian Council to run.

Lind’s thesis: Though we want to believe that dictatorship in the raw is the root of global instability, the biggest source, without a runner-up, is religion. And the nations that present the most danger to their neighbors and their own citizens are religious states.

One tyranny, under God . . .

Iran? Well, of course. Then again, Pakistan’s Ministry of Religious Affairs, Lind points out, observes the motto, “Islam is the only religion acceptable to God.”

Now, that’s a phrase anyone of reason would grant to another’s conscience or congregation. But as government policy it is scary as hell.

“If it is barbarous for South Africa to to be a Nazi-like supremacist state,” Lind writes, “why is it not barbarous for Saudi Arabia to ban public practice of others religions by its citizens?”

Lind is not advocating that secular nations confront theocratic tyranny in the way George Bush, Dick Cheney and Paul Wolfowitz envisioned the “onward march of freedom.”

“The one thing we in liberal countries can do, while reformers in Iran fight and sometimes die for their principles, is to understand our own,” Lind writes.

He speaks of secular principles.

In our society, too often to celebrate the virtues of secular government is to be denounced as “devoid of morality,” “anti-God” or “anti-religion.”

To paraphrase the immortal James Madison: What a crock. The design laid out by our founders resulted in the most lush forest of faith, and faiths, imaginable.

Yes, we have a sectarian paradise. Thank secular government for that. Yet it gets no thanks, or respect, from posturing pols who want religion — their religion — to govern.

True, unlike in Iran we aren’t required to seek mullahs’ consent to run for president. But observe how candidates parade to American holy men for their blessing.

To what public policy ends? To order a pregnant woman to gestate to term? To pronounce personhood to discarded, frozen pre-embryos whose stem cells might save lives? To forbid spousal rights for partners of opposite sexes?

Each of these things a holy man might decree.

So, too, would he carve the words of the Ten Commandments in the courthouse foyer, though annoying secularists might see the biblical “thou shall have no God before me” as philosophically kindred to “Islam is the only religion acceptable to God.”

The sad thing about many people of faith is they have no faith in what they believe. They think that for faith to be strong, government must reinforce it. Pitiful.

What we see in Iran — and Pakistan, and Saudi Arabia, and Afghanistan — should make us all disciples of a government that puts personal belief on such a pedestal that even it cannot rise to tamper with it.

But alas, sometimes it just feels right to distribute helmets and billy clubs.

John Young’s column appears Thursday and Sunday. E-mail: jyoung@wacotrib.com.