In a world with so much cause for doom and gloom, one of the persistent bright spots is the steady growth of the nonreligious, atheists and agnostics. Year by year and decade by decade, organized religion keeps losing strength, while nonbelievers are gaining. Where white Christians once commanded an absolute majority of the U.S. population, with political power to match, they’re now an aging, shrinking minority hanging on by their fingernails. It’s only America’s undemocratic system tha...