"How do you become a fundamentalist atheist? ..." Qcmbr
I suspect that a "fundamentalist" atheist - or, at least, the form of "fundamental atheist" that Christians pose as a "boogeyman", would be someone who would want to force their attitudes and mindset upon others, especially by legislation...
Like the Jews, Christians and Muslims have done, for thousands of years...
And such "fundamentalist" [extremist] atheist legislation would probably NOT take the form of "banning prayer in school", for school is supposed to be SECULAR - a place to learn about FACTS that build the infrastructure that supports our civilization - the physical sciences, electrical engineering, mechanical engineering, and so on.
No, "fundamentalist" [extremist] atheism could be postulated as taking the form of banning prayer EVERYWHERE, even in churches... which is VERY unlikely to happen.
Most atheists are familiar enough with the extreme levels of opression employed by the Middle-Eastern Religious Three down through the ages, to be FIRMLY determined to NEVER mimic the opression that the Jews, Christians, and Muslims have employed to FORCE people to believe in THEIR particular little gods!!
Zid