"Do what mommy tells you now. I just want you to lend me a teeny bit of your power, that's all."
In Game
In the video game, Dahlia was the leader of a cult who seemed to be trying to tap the power of Samuel, a fallen angel or "old god". Her cult seemed more involved in the hidden shadows of the town then in the open due to their funds coming from an illegal drug being sold on the streets.Michael Kaufman was Dahlia's main partner in the cult and the father of Alessa. Kaufman invented the White Claudia, the main source of drug revenue for the cult. The drug was highly addicting that forced some of the addicts to obey the cult since they had little choice to meet their fix.
Lisa Garland, a nurse and obsessive addict, became Alessa's nurse and was forced to keep her silence about the girl as she was being kept in the bottom of the hospital, hidden away from the world. She is the only known and named cult related NPC in the game.
In other games, it is suggested Dahlia's aims and goals were not the cult's true aims, but more personal. That Dahlia was leader of a splinter of the faith which lost their way. The true cult seems to be waiting for their god, a female persona, to lead them into paradise on Earth in a baptism of blood.
Movie
Christabella is the leader of movie's cult, a faith which worships the same female god that the 'true' in-game cult does. This cult was more in the open then it's game counter part, having it's own church and school in the movie. Also, cult members seemed to be able to run and infulence the town.Dahlia was a member of no importance, though Christabella seemed to watch even the least of the cult's members. It was through Christabella's authority in town and in faith that pushed Dahlia on handing her child over to the woman.
They believe in purity through fire.