Carl Sagan’s 1985 Gifford lectures are really interesting. They have been edited and published in The Varieties of Scientific Experience: A Personal View of the Search for God.
I highly recommend this book.
Massimo Pigliucci recently commented on the book at his blog Rationally Speaking (see Good point, Dr. Sagan!). He points out that Sagan effectively issued a challenge to theologians in his lectures. It’s a challenge they have not taken up.