I am some sort of a rationalist, although not perhaps as hard-line as some. I WAS brought up by rationalist atheists, and have discussed with my sister our mutual absolute inability to imagine becoming religious. While our parents' views were always explicit, they were not imposed. My wife's experience is parallel, and she is similarly perplexed by the idea of religiosity. I don't think rationalist parents need do more than love their childrn, and do their rational best to talk rationally to their children about issues that arise. I will say that I consider it irrational to deny the impact of irrational/unexplainable phenomena on our existence- perhaps virulent, foaming-at-the mouth atheism a la Dawkins might enegender a flight into religion in a damaged child.