Would ET affect our religion?
Humans are, overwhelmingly, religious (or at least spiritual) folks. I've read a fundamentalist magazine arguing that ET is not out there, because God would have told us through the Bible, or at least the Bible would not have implied that the universe was made for humanity alone.
I never saw that. The Bible didn't tell us a lot of things, even if you accept it as divinely inspired. If there are intelligent beings, great: we can have a fascinating discussion about spirituality (or lack thereof.)
Apparently there was a very interesting panel discussion on this at SETICon 2. Astronomer Seth Shostak noted, "We haven't been the center of the universe for a while now."
I like what a Baptist theologian (not on the panel) was quoted as saying: "If a couple has one child, and then they decide to have a second child. Is that second child any less special?" In other words, finding other intelligent species doesn't lessen us in a theological sense.
Maybe we can trade missionaries.