NEW YORK – For the first time in its history, the United States does not have a Protestant majority, according to a new study. One reason: The number of Americans with no religious affiliation is on the rise.

The percentage of Protestant adults in the U.S. has reached a low of 48 percent, the first time that Pew Forum on Religion & Public Life has reported with certainty that the number has fallen below 50 percent. The drop has long been anticipated and comes at a time when no Protestants are on the U.S. Supreme Court and the Republicans have their first presidential ticket with no Protestant nominees.

Among the reasons for the change are the growth in nondenominational Christians who can no longer be categorized as Protestant, and a spike in the number of American adults who say they have no religion. The Pew study, released today, found that about 20 percent of Americans say they have no religious affiliation, an increase from 15 percent in the last five years.