Is art or religion under attack?
UPDATE DEC. 8, 2010:
The gallery issued a statement available in full on the Smithsonian's website that said: "Acknowledging that some visitors may prefer not to encounter some of the subject matter in the exhibit, the museum installed signs at both entrances, reading 'This exhibition contains mature themes.'"
The commissioner of the exhibit resigned in protest  over the gallery's taking down of the video in question.
And several museums and galleries have reacted to the decision by screening the video, which just goes to show that if you want to make sure everyone sees, reads, or hears a piece of art, condemn it.
Despite what the rhetoric of Bill Donohue, et al says, the Hide/Seek exhibit at the Smithsonian Portrait Gallery is under attack—not Christianity.
Rather than first contacting the Smithsonian directly to discuss their problems with the exhibit that “focuses on sexual difference in the making of modern American portraiture, ” soon-to-be House Speaker John Boehner and incoming Majority Leader Eric Cantor publically cried foul, issuing statements directly to media outlets demanding that the exhibit be taken down. According to an interview with Lee Rosenbaum  (art critic for the Wall Street Journal and Art Journal’s CultureGrrl ), National Portrait Gallery director Martin Sullivan said that Boehner and Cantor likely haven’t even seen the exhibit (normally the museum receives notification when members of Congress visit; they have not been notified).
Bill Donohue admits to only having seen some of the images of a controversial four minute video in which ants crawl all over a crucifix, but has already claimed that a “simple principle” is being violated by the exhibit, therefore the gallery should lose funding: "If it's wrong for the government to take the taxpayers' money to promote religion, why is it OK to take taxpayers' money to assault religion?"
Sullivan commented, “Eleven seconds of a four-minute video were seen as the entire exhibition. It's a huge exhibition, one of the largest ever at the National Portrait Gallery, with 105 works of art, many of them masterpieces that have been displayed in museums around the world. But that few seconds of video featuring the crucifix became the focal point, and the significance of the exhibition would have been overshadowed by that one piece [had the museum not agreed to remove it].” Sullivan had the video removed from the exhibit, which has some critics claiming he “caved.” 
Hide/Seek has been on display since October 30, so why, more than a month later, is it now becoming an issue?
Two forces seem to be at work here, one being that Republicans are looking for ways to slash the federal budget in ways that don’t include cutting defense spending or the tax cuts for the wealthiest Americans. Rosenbaum told NPR  that while the video is actually controversial, "The problem is that it's such an easy target when they're looking for cuts, when they're looking for differences with the administration, to look at a federal institution—which the National Portrait Gallery is—and try to make that into a big issue." (Republicans even brought a bill to Congress that would cut NPR’s (very marginal) funding just last month .)
Also at play here is the tendency of some Christians (the dominant religion in the United States) to think that they are the oppressed minority, under attack by secular culture, the culture of death, the “lamestream media,” or liberal Hollywood. An image of ants on a crucifix is certainly provocative, but is not an assault on religion. Frankly, the shield and the sword (found in the logo of the Catholic League) or even an American flag and a cross depicted together are just as likely to be interpreted as an assault on Christianity (just talk to a Mennonite). Furthermore, images of Muhammed and images of Jesus don’t even belong in the same category. You can’t compare them. Also, someone ought to remind Bill Donohue how Muslims are actually treated in this country and then ask if he demands equal treatment.
What does a portrayal of a crucifix crawling with ants actually do? Express excruciating pain and suffering? Does it make your skin crawl? Do you want to look away because it is so wholly wrong and disgusting? Well those are things that really ought to be associated with the crucifix. I've never been a fan of images that beautify Christ's suffering, romanticizing it in such a way that it's hard to even imagine him suffering. Traditional portrayals of Jesus on the cross show a societal outcast who suffered the most unhappy of endings. Millions of suffering worldwide—even those dying of AIDS—identify and find comfort in this.