I spent a lot of years in scouts, made Eagle, I still go from time to time as a volunteer leader, so to add to what Moondog said, and to straighten things out:
The scout law is 12 principles scouts are supposed to live by, being reverent is the 12th. By current interpretation, that means you belong to a religion, whether you be Christian, Jewish, Muslim, Hindu, Taoist, Wiccan, whatever. In the old days, professing a belief in god was a prerequisite for joining, but I've never seen that implemented in my time. As far as I understand, as long as you're not an outspoken atheist, and you don't openly make disparaging remarks about other religions, no one will bother you about it.
As for gay people, one big misunderstanding: Scouts (under 18) who are gay are permitted, but leaders (over 18) who are gay are not. For a lot of people this may seem like a matter of semantics, but their decision to do this is partly image, and partly to reduce the chances of sexual abuse occurring (Note: I know most gay men are not pedophiles, but this precaution is taken for the few that are).
Also, third thing, believe it or not, females are allowed in boy scouts to a limited extent. Adult women can be troop leaders, my troop actually had a woman for a scoutmaster for a while. There's also a branch called Venture Crew, which is coed, and for 14-21-year-olds. My younger sister is a part of this.
I realize that some of the choices BSA makes may be disagreeable to some, but I just wanted to set the record straight so people aren't forming their opinions based on misconceptions.