Life on other planets: if life on other planets is found--especially if that life is more advanced than humans--what will that do to religions who insist that they were made in God's image? Will they still think that humans were special? If that life is radically different physically, are they in God's image, too? With evidence to the contrary right in their face, will they continue as they do now, insisting theirs is the only "true" religion?
Or will they rationalize that there is more than one "true" God? I doubt this outcome, but it would be entertaining to watch the contortions they would go through in order to justify that statement.
I think the first scenario is the more likely, and that's pretty darn depressing....it would just give them a larger platform so they could proselytize, try to convert, and start wars on an interplanetary scale (if they are able to).