Atheists consistently attempt to take the higher ground by insisting Christians are mental midgets for believing in a non-existent "sky gawd."
This is an example of what is usually called a "sweeping generalization." You are taking what a few atheists say, and implying that all atheists do that. They don't.
By the way, some theists say rather nasty things about atheists. Should we indict all theists for that?
Based upon numerous court rulings that atheism is religion, ...
As far as I know, the courts are not arbiters of the meaning of words. You have not provided any citations. My guess is that the courts you are thinking about were only making a limited determination of the scope of the establishment clause of the first amendment to the US constitution.
Fundamentalism - the anti-American, anti-Christian branch of American Christianity