Perhaps Christians con't perceive them as, "alien", but rather miraculous or angelic. The Emperor Constantine saw the apparition of a cross in the sky (In Hoc Signi), and of course, the The miracle of the sun at Fatima, Portugaul was well documented, although of course, its cause has never been definitively been established as alien, demonic or miraculous.
Likewise, no less a Christian thinker wrote both fiction and serious philosophical postulation about the existence and moral nature of life on other worlds (and humorously speculated about how human vanity would lead us to proselytize on an Edenic world where the natives had actually obeyed God, and not fallen from grace.)
Having accepted for decades that Fatima was as purported . . .
I’m not 100% convinced it was alien/ET generated hoax stuff start to finish.