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Nearly 20 percent of Americans do not identify with any particular religion, according to a new poll. The number is much higher among younger Americans, according to the survey from the Pew Forum on Religion and Public Life.

For the first time less than half of Americans - 48 percent - consider themselves to be Protestant. One third of Americans under 30 do not identify with a religion. Pew calls them "nones."

In 1972, only 7 percent of Americans did not identify with a religion, according to Pew.

The number of Christians has fallen by 5 percent, according to the survey. Those affiliated with "other religions" has risen by more than 2 percent. And the number not identifying with a particular religion has gone up more than 4 percent since 2007.

Read the Pew report.

Those without a specific religion are not necessarily nonbelievers. In fact most of them do believe in a higher power of some kind.

About 30 percent of the "nones" are "absolutely certain" there is a God or universal spirit. Seven percent of the U.S. population and 27 percent of those not affiliated with a religion believe there is no God or universal spirit.

The number of Americans who attend church "seldom or never" has climbed from 25 percent in a 2003 Pew survey to 29 percent today.

All this paints an interesting picture of American religious life, and according to the survey, could have political consequences. "Nones" seem to favor Democrats.

Here is a passage from Pew's report:

"With their rising numbers, the religiously unaffiliated are an increasingly important segment of the electorate. In the 2008 presidential election, they voted as heavily for Barack Obama as white evangelical Protestants did for John McCain. More than six-in-ten religiously unaffiliated registered voters are Democrats (39%) or lean toward the Democratic Party (24%). They are about twice as likely to describe themselves as political liberals than as conservatives, and solid majorities support legal abortion (72%) and same-sex marriage (73%). In the last five years, the unaffiliated have risen from 17% to 24% of all registered voters who are Democrats or lean Democratic. (See religious groupings in pie chart below.)"

Democrats may do better among those not identifying with religion, but it is still quite difficult to be an elected official in the United States as an atheist. There is only one member of Congress who considers himself an atheist - Rep. Pete Stark of California. But he also attends church with a Universalist congregation, so for the purposes of the Pew study he might not even be considered a "none."

There is a self-described nontheist, Krysten Sinema is running a hotly contested race for Congress in Arizona.

Stained-Glass Ceiling: Would America Vote for a Non-Christian?

Belief in God matters to Americans in politics. A Pew study in 2011 found that 61 percent of Americans would be less likely to support a candidate that didn't believe in God. Only 46 percent would be less likely to support a candidate that had an extramarital affair.

"Though the 'unaffiliated' are not entirely made up of nonbelievers, the fact that one in five Americans have rejected traditional religion means that the enormous influence religion has had over policy and culture will continue to wane," said Ronald A. Lindsay, President and CEO of the Center for Inquiry, which aims to foster a secular society. "Furthermore, thanks to the high percentage of 'nones' among the younger generations, these numbers tell us that we are closer than ever to realizing a society in which religious dogma has no significant influence on public policy-that is, a society based on reason and science rather than myth and superstition."