contracycle, who may or may not be a fundamentalist atheist, has one thing in his favour. It is that he is correct. contracycle pointed out that atheism has no tenets (your word). Therefore there are no fundamentalist atheists. an atheist may be an atheist simply because he woke up one morning following a dream in which he was told to be an atheist, and followed the advice. You don't need to have any rational justification for being an atheist. Being an atheist doesn't necessarily require rationality.
What you are talking about is a fundamentalist sceptic. now a sceptic does indeed have tenets. Being an atheist may follow from fundamentalist scepticism, but it is possible to be an atheist without being a sceptic.
There are tenets to being a sceptic. They include, for example, the idea that you should radically distrust logical statements which are non-sequiturs.
A logical statement takes the form,
if X then Y.
Theists often put rather odd things in place of X and Y.
If I don't know whether God exists, then God exists.
If God exists, then he is love.
If life is complex, then God created it.
etc. etc.
A non-sceptical atheist might say:
If I don't know whether god exists, then God doesn't exist.
(no better than the theist)
A sceptic is rather different. He says:
If I don't know whether God exists, then I will distrust the proposition that God exists.
Being a sceptic is all about DISTRUST. If you are an atheist, you may well have been led to that viewpoint on the basis of your fundamentalist scepticism. But in that case, the "fundamentalist atheist" does NOT use "the same kinds of arguments that a fundamental YEC uses". This is because the atheist is a radical sceptic, while the YEC is a radical believer.
The YEC can believe anything he likes, whereas the sceptic can disbelieve anything he likes.
hope this helps,
mick