The celibate, dancing Shakers were once seen as a threat to society – 250 years later, they’re part of the sound of America

In the Shakers' early years, dance was one of the most distinct aspects of the Christian group's worship. Bettmann via Getty Images

Director Mona Fastvold’s new film, “The Testament of Ann Lee,” features actor Amanda Seyfried in the titular role: the English spiritual seeker who brought the Shaker movement to America. The trailer literally writhes with snakes intercut amid scenes of emotional turmoil, religious ecstasy, orderly and disorderly dancing – and sex. Intense and sometimes menacing music underpins it all: the sounds of the enraptured, singing their way to a fantastic and unimaginable ceremony.

The trailer is riveting and unsettling – just as the celibate Shakers were to the average observer during their American emergence in the 1780s.