Unless you are just in from Mars, you can hardly have escaped noticing the nationwide campaign to eliminate all references to Christmas from the public square.

Not only is government allegedly forbidden, under the First Amendment, to countenance the erection of Christmas trees, let alone creches, on public property, even purely private institutions dealing with the public, such as department stores, are under heavy pressure to avoid participating in activities involving Christmas symbols. Even ordinary public chatter is being cleansed of allusions to Christmas, supposedly to avoid hurting the feelings of non-Christians. Hence "Happy holidays" instead of "Merry Christmas," and so on.

Who is behind this campaign, and why is it happening just now? By far the biggest institutional promoter of the purge of Christmas from the public square is the American Civil Liberties Union, which endorses the interpretation of the First Amendment as forbidding the slightest taint of religion in our public life. There are other interpretations, which conclude that the First Amendment merely forbids the federal government to establish an official state church, as several of the original states had done; but in the 20th century the courts adopted the ACLU view, and lately have been enforcing it with increasing vigor.

This position has the effect of making atheists the default beneficiaries of the First Amendment. Now, atheists represent only a small portion of the population (numbers are difficult to come by, but 10 percent would be a generous estimate), but they are an extremely influential group, heavily represented in various intellectual elites. Hitherto they have chosen to stay safely below the radar screen of public consciousness, but in recent years a significant number of them have begun speaking out more frankly.

The argument between atheists and religious advocates has, of course, been going on a long time. All that has happened is that in the United States today the atheists have acquired at last the critical mass, or perhaps just the intestinal fortitude, to engage their adversaries openly. The dispute has promptly taken political form, and most of the atheists have found haven in the Democratic Party, which tends to treat them as just another victimized minority. The Republicans, conversely, have benefited from the support of many religious advocates, who respond favorably to sympathetic references to "family values," etc. There is, however, an ultra-libertarian wing of the GOP that leans toward atheism, and of course many Democrats haven't yet given up on religion.

The upshot is that the battle is now out in the open. The loud complaints you hear in the media about the "theocons" and the Religious Right are simply the view of the atheists and their allies Ñ people who, though not atheists themselves, have bought the argument that the First Amendment requires them to behave that way in public. Throughout its history, the United States has tolerated a good deal of public religious activity Ñ all of it well short, it should be stressed, of establishing an official religion. But a battle has now begun to eliminate all such activity, and the courts seem disposed to look on the attempt with favor.

Of course, in a nation as overwhelmingly religious as the United States, one impulse is simply to disregard such efforts as beneath notice. And it is certainly true that, as a people, we oppose the official establishment of any religion and seek only comity among the many religions represented here. But it surely cannot be terribly offensive to wish even non-Christians a "Merry Christmas" when all that means is that the wisher believes that something happened in a Palestinian manger 2,000 ago that, properly understood, would give everyone reason to be merry.