Good thoughts overall. I will assume Sagan has deeper thoughts on religion than what he writes here, but I found those parts superficial and overly simplistic. The problem I have with his perspective is that we know from Godel's incompleteness theorem that no formal system can explain its own consistency in the language of the system. As a human, this means that there are things in life we have to accept as true but are fundamentally unexplainable. Religion does not explain the unexplainable but it provides a language and framework in which certain experiences of being alive can be felt and communicated. Both science and religion (to the extent to which these are even different concepts) have positive and negative sides. I personally think the dark side of science is just as dark as that of traditional religion but I don't deny the light or dark contained in both.