But it's not an unreasonable question. Why would you spend so much time talking about something that you don't think exists? I can't speak for anyone else, but here are my reasons.
- It's interesting. Just because something doesn't exist doesn't mean it's not interesting to think about. I also like talking about elves and alternate histories.
- I want to know the truth. If a god does exist, I want to know about that, and I won't find out by sticking my fingers in my ears.
- Finally, and most importantly, because people use their belief in god to support teaching creationism, banning abortion, bashing gays, mandatory public school prayers, and many other flagrant infringements on rights.