I keep coming back to a simple phrase in the U.S. Constitution.

Article VI says there will be “no religious test” for anyone seeking public office.

Isn’t that clear? As in crystal clear?

Why, then, is Donald Trump injecting faith in the Republican Party’s presidential primary campaign by questioning whether one of his opponents, Ben Carson, worships outside the mainstream?

Trump proclaimed the other day he is a Presbyterian. “I’m Presbyterian. Boy, that’s down the middle of the road, folks, in all fairness. I mean, Seventh-day Adventist, I don’t know about. I just don’t know about.”

Carson is a Seventh-day Adventist.

How does this guy get away with saying these things about his political adversaries?

A candidate’s faith is supposed to be off the table. The Constitution — the document that politicians, Democrat and Republican and alike say they revere — lays it out there in stark terms. There must be “no religious test.”

Trump, though, flouts his professed respect for the Constitution while questioning whether another candidate’s faith is mainstream enough to suit the voters both men are courting as they fight for their party’s presidential nomination.

What’s more … the guy is getting away with it!

God help us …