Conservatives might protest that the beauty of God is rooted not in relevance but timelessness. But, like any other business, Christianity is a numbers game - so making that argument sounds like saying, "Yes the car might be popular, but the horse and cart is a design classic." Intellectual momentum, liberals insist, is with love and diversity.

Not so, says Ross Douthat in a New York Times article that has caused quite a stir among the liberal faithful. Douthat charts the strange demise of the US Episcopal Church, which he describes as "flexible to the point of indifference on dogma, friendly to sexual liberation in almost every form, willing to blend Christianity with other faiths, and eager to downplay theology entirely in favor of secular political causes."

And yet, against the predictions of liberal theologians, the result has been the evolution from a pseudo-national church to a hippie sect. "Last week, while the church's House of Bishops was approving a rite to bless same-sex unions, Episcopalian church attendance figures for 2000-10 circulated in the religion blogosphere. They showed something between a decline and a collapse:In the last decade, average Sunday attendance dropped 23 percent, and not a single Episcopal diocese in the country saw churchgoing increase."

This story is familiar across many mainline Protestant denominations. William Briggs' work shows that the Methodists and Presbyterians have all but disappeared in the last twenty years. By contrast, the Catholics and Assemblies of God have slightly increased their numbers and the Southern Baptists are "treading water."

This map reveals an astonishing picture of faith in the 21st century. Thanks to immigration and a steady increase in priests and congregations, the closest thing the US has to a national church is now the Roman Catholics. The only bastions of Protestantism are the Baptist South and Methodist West Virginia. The Mormons have a strong presence out West, too.

What is going on? From the Right, Charles Coulombe has a typically witty article in which he notes that the Episcopalians are doing what they always do, which is to imitate the social values of the establishment. The problem is that the establishment no longer directs popular tastes in the way that it used to. Diana Butler Bass offers a more liberal response, writing that Christianity is declining in general, not just liberal Christianity in particular. The problem with Bass' pessimistic argument is that Pentecostalism bucks the trend. Where it is ultra-orthodox, Christianity is actually flourishing.

The other problem is that Americas' overall belief in God shows no great evidence of decline. What has really fallen isn't faith but patterns of communal worship. For millions of folks, it is no longer the default to join a church. In fact, giving up your Sunday morning to sit in a cold temple listening to a kazoo band playing Nearer My God To Thee is, for most people, a perverse thing to choose to do. Ergo, it is not enough to get them into the pews by saying, "We've driven out the bigots." - ministers now how to convince the public that church attendance is in their personal interest. And conservatives are better at doing this than liberals because the product they are selling makes a stronger claim for its value to the individual.

Think of faith as operating within a highly competitive marketplace of ideas. Faith is no longer a product that people presume they need and are looking to buy (soap or shoes). Instead it has become a luxury item, or something that they have to be convinced that they might want (a sports car or a puppy). What kind of luxury is more likely to sell? Liberal Christianity is wracked with doubt, ducks strong conclusions and often seems to apologise for its own existence. Its liturgy is a confusing blend of styles and belief systems - just take a look at this colourful consecration of an Episcopalian bishop in Los Angeles. What do these people believe, and how is it relevant to me?

By contrast, the conservative Christian product is a zinger. It screams loudly that it is the only way to Heaven, its Protestant services tend to be packed and charismatic, and its theology is straight-forward and uncompromising. In case you think all this business talk is crass, take a look at the way that evangelicalism skillfully pitches itself as a lifestyle. It has become a multi-million dollar industry that offers advice on everything from parenting to drug rehabilitation. Tithing is pushed by some preachers as if it was a pyramid scheme - "You gotta give to receive." This is why conservative congregations grow while liberal ones dwindle. It pays to advertise.

Douthat ends his piece by making an historical case for the value of liberalChristianity through its centuries of good works. It's a fair point, but it betrays a little of the establishment thinking that is destroying the EpiscopalChurch. Sadly, no one in the 21st century remembers or cares that the Episcopalians once helped feed the hungry or clothe the poor.7/26/12 America's liberal Christians might be progressive and inclusive, but they are also dying out - Telegraph...

Dr Tim Stanley is a historian of the United States. His biography of Pat Buchanan is out now. His personal website is www.timothystanley.co.uk