Agree. They've so far been able to reinterpret religious writings to encompass pretty much any development, regardless of how illogical it sounds. I don't think the discovery of life elsewhere would break this trend.
I don't get the whole "aliens are incompatible with religion" bit. I was raised in a Southern Baptist church (yes, I got out as an adult) and AFAIK there's nothing in the Christian Bible that says we're the only planet in the universe with life. Please post book, chapter, verse if I'm wrong.
You're right - they have been able to spin things to their advantage. However, to my understanding, many are still based on the geocentric view of the universe and that we are a very special exception to every other planet we've observed w/o life.
We are just now discovering that planets are actually abundant and are all around us. A thought that seemed alien just years ago when we thought every other star lacked planets.
While I can't predict what aliens will be able to teach/tell us when they arrive (or when we find them), I do feel that a real "first contact" will change or make a lot of people rethink what they really think they know.
To provide just one example, at least one branch of Christianity (Mormons) believes in human-like aliens as a matter of doctrine. If first contact is made with an intelligent species that doesn't believe in the Christian God, they'll probably just send missionaries on an interstellar journey rather than change their faith.
> many are still based on the geocentric view of the universe
And others are not. Individual religions may rise and fall--ironically, the way this happens isn't that much different from biological evolution. But humans have always been religious, and there's no reason that would change, at least not as a result of extraterrestrial life or intelligence.
From a theological perspective, you have to actually make an argument that extraterrestrial life conflicts with doctrine. If you can, I'd like to see you make that argument, because it would be pretty interesting. Plus, theology has a trump card--dogma is always true. And as Quine taught us, it's possible to believe anything as long as you rearrange the rest of your belief system to accomodate it. A man cannot survive inside the belly of a whale, pi is not exactly 3, and the Big Bang and evolution happened--but theologically and philosophically sophisticated religions reconcile these facts with their dogma somehow, and unsophisticated religions pretend the facts are false.
Finding life will be the prequel to finding intelligent life. You're right that finding life itself won't change the views of people who choose to close their minds, but it will be the start of many realizing we're nothing special, but rather, something very common.
Also, I'm almost certain there are life in other planets in our solar system. It'll just take a few (relatively speaking) more years to prove it.