False Ideas Fit for Survival?

I have been reading/listening to some Richard Dawkins and Daniel Dennett lately. These two gentleman are promoting a concept that religion is an infectious idea (a meme, as they call it) that is fit for survival, and has therefore survived through the course of human history. As I was reading through I was wondering about something and thought some of you might like to tackle this idea (either for or against).

Here’s what I was thinking: If, through the process of natural selection, an idea can survive that is fit for propagation, then does that idea necessarily have to match up with reality?

Dennett says that religion is a fit idea that has survived because of its very “fit-ness.” He ascribes the continuance of religion as attributed to the process of natural selection. Throughout his discussion of religion (Breaking the Spell), he is basically claiming that God is false or unknowable (so false in practicality). However, natural selection has advanced and evolved this idea of God. So has the process of evolution given humanity a false, fit idea about God? If this is what Dawkins and Dennett are supporting (of course, not stated that way), then what else might be a false idea that has survived due to “fit-ness” through natural selection?
Thanks,
MJ
Some books related to this matter:
Richard Dawkins, The God Delusion
Alister McGrath, The Dawkins Delusion: Atheist Fundamentalism and the Denial of the Divine – a rebuttal of Dawkins’ book