What if we find extraterrestrial beings? Wouldn't that hurt Christianity a bit/a lot?
Not a bit. The Bible is directed at mankind, on planet earth. As vast as the universe is, as long as we've been searching signals, it would appear that IF there are other planets with intelligent beings - and there might be - we quite likely will never encounter them. If this is the case, it could be that God has already told us all we truly NEED to know, concerning any possible aliens. As if we will never encounter them, this is not a must-know thing. God doesn't tell us everything. But I believe that IF, in the present age, we would one day encounter or communicate with aliens, that He would have prepared us for that in His Word.
The other thing, concerning other physical beings God MIGHT have created - THIS universe and THIS time are, as I've redundantly said, could well be just one book of countless ones God has authored, amongst the countless bookshelves and bookcases He also has filled. God's characteristics, in Scripture, reveal an ETERNAL Being whom is constantly active and loves to create, redeem and restore. ONE 14 billion year span of time is but a coffee break for God. What do we think He was doing in all eternity past? Was the Father, Son and Holy Spirit sitting around bored and playing checkers, anxiously awaiting that future day when He would create THIS universe, time, world and mankind? As His characteristics have not changed, I would imagine He has constantly FOREVER created. So, who knows how many times and universes have come and gone. OR, perhaps, God's other creations have been NON-physical, and thus were in other dimensions or spiritual realms. We might be the ONLY physical creations God has ever made, OR, just the latest in an endless chain of such beings that some either still exist, or no longer exist. It is possible that are other life forms - even intelligent ones - that God has placed in THIS universe - or maybe NOT. There might even be other universes, unconnected, and which we have no ability to detect, that exist now. Or not. God is omnipresent - what does that say about Him existing amongst His own people in Heaven, forever, while also, simultaneously, being active in other places, just as He was in Heaven while the Incarnation walked the earth?
So, just because the Bible is silent on some things, doesn't mean they don't exist or that there aren't many things God has not told us. He told us, all that, in His infinite wisdom, He has deemed appropriate. We so much look at God from a viewpoint of human narcissism - as in, "it's all about us and our time." We just so often fail to realize God has no limits to what He can do or has done in eternity past. Eternity that goes INFINITELY the other way on the timeline of history. As if that doesn't boggle the mind enough, just imagine what a Being with unlimited power and creativity might have been doing in that eternity past. Of course, I'm referencing this as time, which God transcends. As for myself, I'm agnostic on the existence of aliens elsewhere in the universe. Perhaps they are only dust worms on some moon somewhere?