Whatever the truth of such claims, Satan will do anything to bust Christianity’s bubble in the minds of the world that the Restrainer would allow.
Christianity isn’t diminished should some aliens come to town. Humans still have to reckon with God in the way Humans have been commanded to be reckoned thru Jesus. Other alien life would have their own dealings with God as God made them and has provisioned them spiritually.
Should these “aliens” be demonic as it seems much of such events appear to be, then what of it...they are probably of that number that will be thrown to Earth along with Satan in the tribulation era. The Bible explains what will happen and what must be done to avoid taking the mark of the Beast, even if it means death.
Nothing changes for the believer except perhaps increased persecution and in dealing with a much higher level of delusion to be found in non-believers.
That's true in that Christ himself won't be changed and the Truth won't be changed.
But aliens (demons in disguise) could change reality so much that many people would have no idea what to believe. It could rattle people down to their very essence.
Remember Luke 21:26:
"Men's hearts will fail them for fear and for looking upon those things which are coming on the earth; for the powers of heaven shall be shaken."This could make the changes Cortez wrought on the Aztecs look like a backyard BBQ by comparison.
That's why I think it's a mistake for people to "pooh-pooh" this stuff. It may signify nothing...or it may be the sign of something momentous (and not in a good way).