I too am an atheist, and I have two children.
My children do not believe in a god either, not because I taught them not to believe, rather god is just never mentioned.
Being an atheist is the DEFAULT position.
They received the normal religious education from school, but without some reinforcement at home (it is never discussed), they remain unconvinced.
They have not been brought up in a bigoted environment, but brought up to think for themselves.