Lauren Sandler is the author of Righteous: Dispatches from the Evangelical Youth Movement. She has contributed journalism and opinion about culture, politics, and religion for many publications, including The Atlantic, The New Republic, Slate, The Nation, Mother Jones, and The New York Times.

From subway ads to “Blasphemy Day,” nonbelievers are proselytizing louder than ever. But as they draw more converts, are they in danger of losing their unique brand of faith?