To many there wood be. God killed the unicorns and such with a flood, why wood the aliens not be an evil creature? Jesus has to come with the aliens for them to be seen as angels, or the most powerful human militaries wood start launching missiles at one another for random reasons such as "being on satan's side" if they are okay with the dark angels that have reveled themselves to us. Satan could jump in and out of hell after all, it's going to make tons think they are angels sneaking into earth while god is waiting for them to fight the good fight, to fight as christian soldiers the armies of darkness, so then they'd attack while screaming for jesus to show up. Also, if it were the middle ages they'd have killed any unicorn they came across. Because it's' a satan.
That's how it wood play out. For many. The bible cruelly tests men and plenty wood deem this a test. It's why they make shows like V while I'm on tv shows, because I'm the one that brought up the supernatural episode, a main character is a literal priest in that and does NOT trust the aliens, then it basically shows the ays to be problematic like humans and I kept eye rolling and never finished the show, as they acted too much like people, but the point is that human religious people are blatantly though to see aliens as bad. Like with Signs being a better example. That is a blatantly christian show.
In fact the majority of alien fictional movies are about them trying something insidious on us. Only the tv shows attempt showing them as perfectly fine, like with stargate, then it turns around and goes full Egypt = bad on you, as they didin't believe in god so if Egypt were made by aliens then ergo they were A SATAN WITH A CREEPY VOICE TO ENSLAVE THE PEOPLE and eyes glowing and all. Wraith in stargate atlantis eating people, and they never bring up what they believe in becasue to be an atheistic aliens it to serve satan "as you cannot serve two masters". There is zero neutrality in the christian war mindset. Armies of dark vs light. The aliens wood have to cater to that and adopt christianity or face the wrath of the US mlitary, the Russian military, the UK military, the French military, etc, as they have insurgents within their ranks chimp the truck out.