First of all, what the hell? I’m defending teaching atheism on the grounds that it deserves the same standing as teaching religion, and you come in and act like I’m attacking atheism. I think you missed my point.
Second of all, I think you’re wrong anyway. I am familiar with the principles of logic. In fact, there are many systems of logic, not all of which need be applicable to the real world. Deductive logic doesn’t contain any principle of the form “it’s irrational to believe something without evidence.” Other systems of logic may, but which of these systems should be considered to apply to the real world is the subject of much debate. (Why do you think there’s a branch of philosophy called “logic”?)
Furthermore, what evidence do you have for the assertion that it’s irrational to believe something with no evidence one way or the other? None, I suspect – it’s your opinion. My opinion is that it’s irrational to believe something in spite of significant evidence to the contrary. Moreover, I’d say it’s irrational to believe something for no reason. But if someone’s gut intuition tells them there’s a God (for example), then I’d say trusting that intuition (which has given them verifiably correct conclusions with regard to other matters) isn’t irrational, given that they have no evidence to the contrary. Hell, I’d say that’s the same reason I believe that the data received by my senses corresponds to a physical reality – I don’t have any evidence that it does, but my gut feeling is “the world is real.” I’m going to believe that until presented evidence to the contrary. (Note: I’m not saying people should believe things based solely on their gut feelings, only that to do so is, in my opinion, not irrational – and I certainly don’t think there’s universal concensus that it is.)
But, this is a huge digression: the point of my comment was to suggest why someone would want to instill atheism in their kids. (which you said you didn’t understand) My answer was that it’s for the same reason that someone wants to teach their kids religion – they’re passing on their beliefs. But if you already think belief in God is irrational, then why the hell wouldn’t you understand someone wanting to steer their kid away from an irrational belief?