The Nones, Dones, Unchurched, spiritual but not religious (SBNRs). Call them what you will - they're a dominant force in American religion and the plurality among Millennials and Gen Zers. In Church Tomorrow? Stephanie Spellers presents hard truths about declining religious affiliation in America, paired with stories and wisdom from her interviews with dozens of young people who either grew up with no faith or gave up formal religion. Along the way, she joins hundreds in a yoga circle at San Francisco's Grace Cathedral; in Atlanta, Georgia, she attends Sunday Assembly, a secular congregation that caters to agnostics and atheists; just outside the Twin Cities, she interviews college students exploring crystals and tarot decks; and in New York City she comes home to meet spiritual-but-not-religious young adults who once attended her own church. And that's only the beginning.