Oh, aren't you clever.

Well, I'm glad that you went this way... its not 100% the new direction I was going to take but its close enough that you won't accuse me of being a scoundrel for changing the subject. First to some of your points:
"It is interesting that you choose to focus so much on comparing secular worldviews unfavourably with Christianity on the basis that they ascribe too much inherent goodness to humans, because that seems to me to be only valid in a very narrow interpretation of Christian scriptures."
I'm not sure what is behind this. The truth is that narrow or not, it has been the interpretation always and forever. Its a bit hard to be a Christian- accept the atoning death of Jesus for your sins- if you do not think that you are a sinner. And its hard to extend that offer of forgiveness to every other person if you think some of them may be exceptions. But we don't take man's sinfulness on 'faith' (as Dawkins understands the term). The evidence is in front of our eyes each and every day, and the more one self-evaluates the more one sees that they are not an exception.
"Another reading would say that Christianity ascribes much loftier values to human beings than any system which has evolutionary theory as its explanatory framework for why we're here."
If I understand it right, you're concern is not necessarily that I'm invoking 'original sin' but that the 'narrow reading' you think I'm taking ignores some of the more positive things to be said about humans. That is probably just an unfortunate reflection on the nature of the things you and I talk about- we don't tend to get around to these higher things.
I certainly agree that Christianity thinks more highly of humans than any evolutionary theory.
"People, in that view, are after all created by God - favourites of his creation, made in his own image."
Yes, absolutely. That's Genesis 1-2, and then comes Genesis 3.
Now, even in the fall, it is not contended that we are no longer created by God or that the image is abolished. The image is corrupted, which means a lot of things that would have been easier pre-fall are going to be difficult post-fall, even in the best of situations.
I like how you're using my Creationism against me. :) I really believe this stuff- what would you say to the liberal, englightened modern theologian that has sent this stuff off into the trashbin of myth? These principles are very hard to extract without Genesis 1-11 in them (even when the principles surface later, they refer back to Gen 1-11 as being real history).
Keep that in mind: the only Christians that you can expect to have a solid, Scriptural basis for a high view of Man are those bluming radical fundamentalists d--n them to hell! Many other Christians obviously do have a high view of man- but on what basis?
So, moving on, let me fully affirm that I take the high view of man, but that I also understand that man has fallen. And the higher something is, the further it can fall. Think about that.
"Doesn't evolutionary theory perfectly predict the kind of bad behaviour which you seem to think that only Christianity can explain?"
Oh, I don't necessarily think that only Christianity can explain it. And I definately think that evolutionary theory perfectly predicts bad behavior. You no doubt remember conversations where I tried to point out that evolution not only predicts the bad behavior but that it does not predict that animals should develop a notion that certain behaviors are bad in the first place.
Ie, we can say apart from the Christian scriptures that we intuitively know that humans are 'higher' even while we are face to face with their barbarism. Humans are more vicious even than animals. How many species create weapons of war to destroy other members of their species, are not content to merely kill their young but will go into the womb to do it, will murder just for fun, etc? Evolution is perfectly compatible with this (except for our wonder as to why humans- of all evolved species- are generally more cruel to their own than other species are to their own) but not with notions that this is 'wrong.' Not merely 'bad' or 'detrimental' but 'wrong.' Nor is it compatible with the intuition that we are somehow 'higher.'
Now, let's apply this to the palestinean situation...
But tell me why I should? What right do I have to impose my high views of man (and the low views, if you like) on the people in Palestine who are predominately Jewish and Muslim? On what basis can I tell either the Jews or the Muslims what they should do, or what is right or wrong of them to do?
Morality is merely relative by your view, yet you wish me in this instance to ignore the view that YOU think is true and operate on a view of my own which you think is false- that it is somehow objectively wrong to... perpetrate things such as this: "your country occupied, your house destroyed and your neighbour/wife/auntie shot"
How is it that in a relative morality, you, the secular humanist, request me, the Christian creationist, to impose our collective will on either the Jew or the Muslim, as though for all four of us we ought to acknowledge such things as 'wrong' ?