And the bit I am most interested in:
I tend to find comparative religion interesting for the way in which they can construct a motivation for choosing the "pre-rational" belief of human life having intrinsic value.
In many, of course, the idea of an after-life reward is an obvious motivation.
But going back to this week's topic of Buddhism, I always have had a problem with understanding how it reconciles its teaching about the illusory "non-Self" nature of self and its ethical teaching about that you should treat other "non-Selves" well. Some pro-Buddhist advocates sell its view of the self as entirely consistent with modern, scientific materialist's views; but if so, it seems to mean that Buddhism loses the benefit that I see in other religions of providing a "pre-rational" motivation for treating all humans as having value.
If recall correctly, in Frank Tipler's The Physics of Immortality, he argued that games theory provides a basis for ethical behaviour being entirely rational (and therefore having no conflict with science) but his views are pretty eccentric, and I am not sure that there is any widely accepted view games theory means the "pre-rational" belief of intrinsic human value is in fact rational (or, perhaps, a necessary conclusion of rationality.)
I have been thinking about this for a long time. The distinction between "pre-rational" and rational arguments was basically behind a university essay (or was it during an exam?) on Rawls and his A Theory of Justice. I thought it a very fine effort at providing a rational argument towards what you might call a universal theory of ethics; but I remained unconvinced that it showed why alternative uses of rationality with harsher conclusions towards fellow humans were not just as valid. I was still feeling that it didn't really work to show why the "pre-rational" judgement of the value of humans was something that must be adopted.
I suppose you can take two attitudes towards this - argue that rationality can never resolve the matter, or (like Tipler, or Kant) argue that rationality can lead you to the "right" conclusion about human value. I am inclined to be on the side of the latter.