Dennett's Breaking the spell

Finished reading Daniel Dennett's Breaking the spell yesterday. The problem with Dennett and Harris (and probably Dalkins) is that their writing assumes that man is naturally a rational creature. I think this assumption is as open to question as whether man is naturally good or naturally evil. For all of the rational arguments these folks make, it seems to me that they are either preaching to the choir, or lecturing a room full of monkeys--in either case, however well and ordered their writing and thinking, it's useless.