Nowhere in the 3.0 or 3.5 SRDs does it require druids to worship a deity, and in both editions, clerics may choose two domains not opposed by their alignment if they have no deity. I realize ethos clerics are debatably unbalanced, but I believe that, in accordance with the rules, people should not need a deity to become druids. -EE
I'm afraid class requirments are hardcoded in the game. As such, I don't see atheist druids coming very soon, sorry.
There is an option of having no diety in the internal files, but I can't remember if u ever have the option of choosing it on the character creation screen. {0}{None} // diety {1000}{Agnostic or Atheist. In either case, nothing is coming to help you in your time of need.} // expanded description {2000}{Agnostic or Atheist.} // simple description {3000}{I rule!} // invoking the diety
I just created a Lawful Neutral Druid and had three choices for diety, one of which was none. I choose this and the character created just fine, gonna go play with clerics now. You need to pick a diety for clerics, but... there are console commands and it can be altered later if it adds to your playing enjoyment