If they are not aware of god you are essentially doing the same, unless you suggest we teach them of the 20 plus religions, plus athiesm or other variants?
You can't teach atheism. Atheism is the null hypothesis, the rejection of theist suppositions. What you can teach is critical thinking, to evaluate claims using what evidence is available.
Of coarse if you are raised as a blank canvas you will more than likeley become an athiest, what you learn as a child is the most important things that will last with you forever. its perfectly reasonable to suggest if you are raised devoid of god, you will see no need for him as an adult.
You also learn about Father Christmas and the Easter Bunny as a child. However, we disregard them after a certain point because we decide that the evidence does not support the existence of these beings. We have lost faith in them. Quite rightly too, this is how critical thinking works. However, a respected and trusted adult reinforcing a belief despite a lack of evidence flies in the face of a child's critical thinking. There is a conflict and it is resolved by critical thought becoming less relied upon by the child.
If the evidence is compelling enough, an atheist will turn to belief. Atheism is a rejection of belief based on a lack of evidence, but clearly new evidence would have to be evaluated critically and their position reevaluated. No compelling evidence has ever appeared. I must state my position here. I am an atheist. More specifically, I am an agnostic atheist. Based on the evidence, I believe there is no God but I can't know this for certain. I accept that I could be wrong, but any rationale for changing my position would be based on evidence and critical thinking, not faith.