First up from the God Machine this week is a striking study on a new trend in American religiosity. As NBC News’ Erin McClam First up from the God Machine this week is a striking study on a new trend in American religiosity. As NBC News’ Erin McClam reported this week, the percentage of the population that does not identity with any religion has grown dramatically in recent years, as the Christian population in the U.S. shrinks.

The Pew Research Center found that 22.8% of Americans were religiously unaffiliated last year – up from 16.1% in 2007. That group includes atheists, agnostics and those who chose “nothing in particular.” Evangelical Protestants made up 25.4% of the adult population, down slightly from 26.3% in 2007. Catholics declined to 20.8% from 23.9%, and mainline Protestants to 14.7% from 18.1%. In all, roughly seven in 10 Americans identified with some branch of Christianity, down from almost eight in 10 in 2007. The share of Americans who identify with a non-Christian faith grew to 5.9%, with pronounced growth among Muslims and Hindus.

The full report from the Pew Research Center is available online here . Note, in the chart I put together, “Non-Christian Faiths,” refers to Jews, Muslims, Hindus, Buddhists, Sikhs, and others, which combined now represent nearly 6 percent of the U.S. population.

For those discouraged by the overall drop in American Christians – the population has shrunk by roughly 5 million adults, just since 2007 – the results are probably even more alarming when age breakdowns are considered. The Pew data found that while there was a drop in Christian affiliation among Americans of all ages, it is “particularly pronounced among young adults.”

For Americans born in the 1980s, a third of the population is religiously unaffiliated. For those born in the first half of the 1990s, that number rises to 36%, narrowly behind Protestants at 38%.

Not surprisingly, the publication of the report has sparked considerable conversation, including in the political world, where Rush Limbaugh blamed President Obama for the recent shifts – as if the results were necessarily discouraging and in need of a culprit bearing responsibility – while Bill O’Reilly pointed the finger at “pernicious” entertainment he doesn’t like. (I tend to think the politicization of religion is itself, ironically, a key factor in the recent trends.)

But whatever the cause of the shifting religious landscape, the political and cultural impact is likely to be significant. The New York Times’ Nate Cohn explained , “Conservatives and Republicans, for example, have traditionally relied on big margins among white Christians to compensate for substantial deficits among nonwhite and secular voters.”

We tend to think of the GOP’s demographic problems as related to race: Republicans tend to rely heavily on white voters, which is a long-term problem in a country with increasing racial and ethnic diversity. But the religious demographics matter just as much: Christian conservatives are a key pillar of the GOP coalition. As the share of American Christian population falls, the pillars weaken.

Also from the God Machine this week:

* Seems like the right move : “ An appeals court has overturned the sabotage convictions of an 85-year-old nun and two fellow peace activists who broke into a facility storing much of this country’s bomb-grade uranium and painted slogans and splashed blood on the walls.”

* The announcement from the Holy See caused a stir: “The Vatican officially recognized the state of Palestine in a new treaty finalized Wednesday, immediately sparking Israeli ire and accusations that the move hurt peace prospects.”

* Phil Plait wrote a striking report this week on efforts to push creationism in Louisiana schools (thanks to my colleague Will Femia for the heads-up).

* I’m a little surprised the state didn’t back down sooner: “An atheist in New Jersey has won the right to sue after she was allegedly denied a request for a vanity license plate that read ‘8THEIST.’”