Decline
Over the past two decades, the share of U.S. adults identifying as Christian has fallen sharply — from 78% in 2007 to just 62% in 2023–24, a drop of 16 percentage points. In that same period, the proportion of Americans who say they are religiously unaffiliated (atheist, agnostic or "nothing in particular") has risen from about 16% in 2007 to 29% today. - Pew Research Center