More than a quarter of U.S. adults do not affiliate with any religion, according to a Pew Research Center study released Wednesday.

Why it matters: In keeping with a global increase in the number of people without a religious affiliation, the figure reflects how the once powerful force of religion continues to dwindle in influence.

By the numbers: About 28% of U.S. adults do not have a religious affiliation — a group referred to as "nones" — based largely on a 2023 survey of 11,201.

• For comparison, 40% of Americans identify as Protestant and 20% as Catholic, per the research center's latest figures.

Between the lines: Among the "nones," most described their religion as "nothing in particular," while a fifth described themselves as "agnostic" and 17% as "atheist."

• "Nones" make up younger populations, with 69% below the age of 50.
• The majority of "nones" are white, and there's a near split between men and women, at 51% and 47%, respectively.
• "Nones" are also more likely than people with a religious affiliation to identify as "liberal."

Meanwhile, two-thirds of the group cited nonbelief, skepticism or a combination of the two as the main drivers for not being religious.

Zoom out: In 2007, "nones" accounted for 16% of U.S. adults, and that figure has steadily increased.

Our thought bubble via Axios' Russell Contreras: The number of religious "nones" appears to be growing with each generation, and current trends show that number could surpass all Protestants by mid-century.

Go deeper: The world's departure from organized religion