So? Why would these Christians be shaken in their belief, when there were already written considerations about the "original sin" and "Gospel" for the aliens?
I don't understand what your disagreement is.
Note: the "World" of the Bible is just a piece of the Mediterranean Sea and the piece of the Near East. Ditto for Quran. Even the whole continent (America) is not known among the people of these books, so these apparently "eternal" books don't know about that fruitful continent either.
But these faiths survived the discovery of the America. And interestingly, the more "fundamentalist" believers actually left Europe and kept their fundamentalism in America and the effects of that we feel even now.
At least the result was that the modern science (trust what is, not what's in the "eternal" books) progressed in the lands that used the "new" resources.
Aition: a tale devised to explain the origin of a religious observance
Even from the perspective of fundamentalist Christianity, which I'd hazard a guess many people would tend to assume to be the most hostile to the idea, there's no reason to believe there aren't aliens somewhere out there. It gets more complicated if fallen humanity is allowed to interact with those other species, but even then you can argue either way within that axiom set.
Really, I'd say the reason that most of us, religious or otherwise, believe "we are the only life in the universe" (or "observable universe") is because that's the simplest explanation that fits the facts. It may well be wrong, but at the moment, there's not even a whiff of convincing evidence that we are not alone, even as we must also all acknowledge there's plenty of room in the "gaps" for alien life, even intelligent alien life, even intelligent alien life that spans several star systems. It depends on how far away we're talking, but even fairly close to home it could take a Kardashev level 2.3-ish at a minimum for us to be sure. No matter what your ideological disposition may be, there's just a huge "NO DATA" out there right now.
That's a religious argument. It's unprovable and unknowable.
Well, if at first you don't succeed, try, try again. Right?
We have to assume that any creation-capable deity has to be patient enough to try the cosmic life-evolving minigame at least twice before quitting forever, right?
"This game sucks. I never should have programmed it. After a couple billion years, I always get the atheist bad ending, no matter what I try. One star."