One of my closest friends, a reasonably intelligent person with a college education, is a creationist solely (as far as I can tell) because he was raised as one. I'm not sure if he's just too lazy to challenge his own beliefs, and I haven't actually talked to him about this in a long time so maybe he has by now. When we did talk about it, my basic scientific evidence was met with platitudes and the word 'faith'. I don't particularly care what he thinks and those sorts of conversations are a waste of time, so I dropped it pretty quickly. The real crime is that parents begin their children on religion at the same age they begin them on fairy tales. That should tell us something.
I suppose you have a pretty good point there. Children are the easiest to manipulate and if one can stick something in their mind it's likely going to stick there for the rest of their lives. Sunday Schools as kleinbl00 mentioned must have played a major role in the development creationism. Looking at the US religion page it dawns me that majority of US Christians are either catholic or baptist. The prevalence of creationism is starting to make sense to me then. To compare: 97% of the religious population here is evangelical lutheran and the church itself accepts evolution theory without conflict to its teachings. In fact I'm officially evangelical lutheran too. My children wont be.