atheism

I just picked up my 9-year-old daughter from her first day of summer camp run by the city, and she told me that Good News Club is going to be preaching to them for five days straight. It's not optional, and it's happening inside the facility. She was not given the option to sit out, though she said if the option had been given to her, she wouldn't have sat out anyway, because she didn't want to be singled out from the other kids. We've been doing our best to raise her without religion, teaching her the basic bible stories (and other religions' stories) from a mythical perspective.

Is this legal for them to be doing? The camp is run in a city-owned building, by city employees.