“I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character.” — Dr. Martin Luther King, Jr.

Sometimes, you get the feeling that’s the only King quote conservatives know.

They can’t quote what he said about unions: “We can all get more together than we can apart.”

They can’t quote what he said about poverty: “The solution to poverty is to abolish it directly by a now widely discussed measure: the guaranteed income.”

They can’t quote what he said about injustice: “America has given the Negro people a bad check, a check which has come back marked, ‘insufficient funds.'”

But they always quote the “content of character” passage from King’s “I Have a Dream” speech. They see it as supportive of their ideal of a so-called “colorblind” society wherein race — and racial problems — are acknowledged never.

Sarah Palin is the latest. Last week on the King holiday, she quoted that passage on Facebook and added: “Mr. President, in honor of Martin Luther King, Jr. and all who commit to ending any racial divide, no more playing the race card.”

You will hear President Obama talk about race only slightly more frequently than you will hear Mitch McConnell say, “Get down with your bad self!” so there was a moment of disconnect in trying to figure out what she was talking about. Apparently, the reference was to a piece in last week’s New Yorker, where Obama acknowledged that there are “some folks who really dislike me because they don’t like the idea of a black president.” He also said some people probably cut him slack for the same attribute.

By now, most thoughtful people would take both observations as self-evident. And you have to wonder: If this mild remark is “playing the race card” what, then, may we permissibly say about race in Palin’s ideal world? Apparently, nothing.

Thus, you will wait in vain for a conservative to speak against the profiling of Trayvon Martin, the mass incarceration of black men under the failed War on Drugs or, ahem, the myriad racially tinged attacks against President Obama. Indeed, other than their cries of pious indignation when some black conservative is mistreated, you’ll wait in vain to hear them say anything about race at all.

To acknowledge that we did not overcome, to admit there are miles to go before the Promised Land, is to play the dreaded “race card.” So, mass incarceration? Don’t talk about it. Racial profiling? Hush. Economic exploitation? Ignore it and it will go away.

You have to wonder, as conservatives make their belated embrace of Martin Luther King, if they realize they are what he struggled against all his life. They’ve never been on the right side of history where black people are concerned. So where do they get the idea that they have moral authority on the subject of black struggle? Where do they get the temerity to shush those who have labored in — and lived — that struggle for years, generations and lifetimes?

The silence they preach is not golden. It is poison. It is moral cowardice.

But it is not new. The race card? Though that term did not exist in his lifetime, King was familiar with the argument. His focus on racial injustice, said critics, fanned flames of racial tension.

To which King said this: “We who engage in nonviolent direct action are not the creators of tension. We merely bring to the surface the hidden tension that is already alive. We bring it out in the open, where it can be seen and dealt with.”

Another quote most conservatives will not know. Too bad. If they understood it, they might better understand the man they purport to embrace.

“Our lives begin to end,” said King, “the day we become silent about things that matter.”

(Leonard Pitts is a columnist for The Miami Herald, 1 Herald Plaza, Miami, Fla., 33132. Readers may contact him via email at lpitts@miamiherald.com.)

Photo: Gage Skidmore via Flickr