NBC:

One in five Americans — and one in three of adults under 30 — is religiously unaffiliated, the highest percentage ever, according to a Pew Research Center study released Tuesday.

Over the past five years, the study found, the number of religiously unaffiliated adults has increased from slightly over 15 percent to just under 20 percent, a figure that includes more than 13 million self-described atheists and agnostics, as well as almost 33 million adults who do not identify themselves with a particular religion.

Survey takers were able to choose from a list that included more than a dozen possible affiliations, including “Catholic,” “Protestant,” "Orthodox," “don't know” and “nothing in particular.”

But, according to the nationwide survey, many of the 46 million unaffiliated adults or so-called "nones" are spiritual or religious in some way:

• 68 percent say they believe in God.
• 58 percent say they feel a connection with nature and the Earth.
• 37 percent say they think of themselves as "spiritual" but not "religious."
• 21 percent say they pray daily.

As you might expect, the number of religious unaffiliated rises as the age group goes down, and the further left you go.  32 percent of adults under 30 saying they're religiously unaffiliated, compared with only 9 percent of those aged 65 and older.  24 percent of the Democratic and Democratic-leaning registered voters are religiously unaffiliated.