I ONCE SPENT Christmas Eve at St. Elizabeths mental hospital.

I'd been studying the patients for a month, and it seemed a great opportunity to put a good deed in the bank.

I knew it would be a downer -- not just the urine smell and the screaming, but that gray miasma of depression that drifts through those wards like the smoke from a New Jersey Meadows dump fire, like the air in a 3 a.m. bus station. But that was the whole point.

Think (I thought) of the moral profits to be gained, the karmic credits, my good deed for the year! There I'd be, Mr. Noblesse Oblige, flexing my charitable smile at the Thorazine fog and knowing that my reward would be bragging rights about my generosity for the rest of my life.

If I'd thought about it more -- as I have since -- I would have realized that I was aspiring to a peculiarly American brand of sainthood, one that we've seen a lot of at Christmastime, lately. Its aspirants hold to the doctrine that as long as one person in the world is cold, wet, tired or hungry, they have no right to rejoice. However, they do have the right to go public with this stand and make us all feel guilty.

This guilt is the puritanical mother lode that Mitch Snyder and his Community for Creative Non- Violence are mining when they threaten to sue if the Pageant of Peace on the Ellipse doesn't include their statue of a black homeless family huddled over a steam grate, along with the inscription: "Still no room at the inn."

This is the guilt that a Maryland protest group tapped into when it picketed Toys-R-Us in Langley Park recently, as part of their International Days Against War Toys. By their very presence they told us we should be ashamed to buy toys based on the movies "Rambo," and "Star Wars" or the "Masters of the Universe" cartoon characters. Note that all three are stunningly moral -- Armageddons in which good always wins. But our children, we're told, have no right to delight even in triumph over evil, if it means the use of violence, however symbolic.

And early this month, the Americans for Democratic Action checked in with their 14th-annual death-toy survey, warning, as usual, that one of the most popular toys on the market can maim or kill America's children. This year the toy is the Cabbage Patch Koosa Doll, because it wears a collar that a kid could remove and put on. In one incident, the ADA said, a 6-year-old girl nearly choked.

The left has no monopoly on sanctimony, wet-blanket-hood and condescension. Witness Phyllis Schlafly and her Eagle Forum telling the media how they sit around a dining room table in a wealthy suburb of St. Louis and make up "Freedom Fighter Friendship Kits" for contras battling the communists in Nicaragua. The kits contain food, medicine and foot powder -- the latter, one volunteer said, for "when their feetsies in their bootsies start hurting."

Meanwhile, back on the other side of the aisle, the memory lingers of the American Civil Liberties Union's battle to keep poor old Pawtucket, R.I., from including a creche in their Christmas decorations in past years. It's hard to imagine the ACLU was really that worked up about freedom-of-religion issues -- if they had been, they might have picked a case they had a chance of winning in the Supreme Court.

But like the hucksters baiting children to telephone Santa long-distance at 50 cents a call, and the advertisers telling us we can find comfort, joy and maybe even peace on earth by buying everything from Chanel No.5 to the Voltron Skull Tank, the moral profiteers have a hard time passing up an opportunity like Christmas.

Granted, the media make a nice warm nest for these albatrosses by running all those stories about Christmas depression, Christmas evictions, Christmas poverty, Christmas car crashes, Christmas trees catching fire, and so on. These stories may wallow in irony -- providing, as they do, a chance for reporters to be tough and sentimental at the same time -- but they're more an attempt to gather together the Family of Man than to make us feel bad for feeling good.

Moral profiteering is not to be confused, either, with remembering the neediest, donating food and clothing to the poor, joining carol sings at old folks' homes, giving a quarter to a Salvation Army Santa Claus or any other of the other splendid gifts of matter and spirit that arise from the primal delight that human beings take in helping each other. With this sort of charity, we are invited to help, to do something, to celebrate Christmas with our generosity.

The moral profiteers of Christmas don't give us that chance. They just want to make the rest of us feel bad. Why don't they save it for Lent? For Yom Kippur?

For one thing, they wouldn't have the leverage they get when there are kids involved.

Another holiday that the bad-news types have tried to ruin is Halloween, sending children out to gather money for UNICEF instead of candy for themselves, and warning that candy-poisoning perverts lurk behind every jack-o-lantern. And now Thanksgiving is being exploited as a time for dwelling on world starvation.

The modus operandi we're talking about here is acedia -- an old word that Evelyn Waugh once defined as "refusal of joy," a version of Scrooge's "Bah, humbug!" masked by the thin smile of self-satisfaction.

The holidays are a season of joy and salvation. We are saved by Christ, we are saved by the sun coming back after the solstice on Dec. 22, we are saved by the tradition we honor when we stand around the Hanukkah lights.

Who are we to complain? Why shouldn't we rejoice in the humanity and the divinity of the people on the steam grates as well as the pink- cheeked children in Norman Rockwell paintings? They're all God's work, and we have no right to be anything but grateful. Moral profiteering is the equivalent of the commercialization of Christmas -- an empty temptation.

All of which takes me back to St. Elizabeths on Christmas Eve.

I am happy to report that there were no moral profits to be made.

I took my high and earnest pity into the ward, and for half an hour or so I was the most confused person there. The screaming had stopped, the urine smell was gone, and the fog of depression was cut nicely by a record player to which these chronics and acutes, these hopeless schizophrenics and bag-ladies-in- waiting sang, smiled and danced with an ease I'd never seen them have -- with joy, even.

I was stunned. How could this be?

I finally got the answer from a psychotic depressive I'd gotten to know, a grieving specter of a woman who spent her days standing outside the dining room, waiting for another meal that she didn't really want.

"You're not dancing," she said.

Well, no.

"You have to dance," she said. "It's Christmas!"

She held out her arms, I took her hand, we danced, it was lovely, and she was right.