Dalish.
Are there any ... atheist Dalish? :/
I don't think anyone can truly be an atheist in the Dragon Age universe. You can really only be an obstinate fool. I think the farthest effective theological "Backpedaling" that can happen in Dragon Age (And in fact, just about every Fantasy Universe ever created) is being a Deists. On some level you have to acknowledge the supernatural forces which manifest themselves daily and objectively.
Then again, this is filtered through modern perceptions of religion having a monopoly on matters of spirit and the numinous. (Sam Harris' words not mine, in case anyone thinks I sound rather smart) In Thedas, the matters of Spirit (The Fade) and creation (the Gods) may in fact be separate matters entirely to some cultures. That could be the case for the Dalish, but I'm rather dumb when it comes to interpreting what the Dalish believe.
Thinking about above, I really think Solas might have some fascinating input on the subject, but maybe I'm getting ahead of myself.