https://www.christianpost.com/voices/unmasking-ufos-aliens-and-demonic-deception.html
Demons want humans to interact with them in order to draw people into the spiritual clutches of the occult. If you open a wrong door in the spiritual realm, demons will come through it to trick you, oppress you and lead you away from the one door that leads to everlasting life in Paradise. Jesus said, “I am the door; whoever enters through me will be saved” (John 10:9).
Interestingly, many “alien” abductees are told they were chosen because they are special and are needed to spread the message of their “alien” abductors. An obsession with UFOs and “aliens” can even become a substitute religion. For example, the Heaven's Gate cult was a UFO religion that produced mass suicides by its members in 1997.
While demons distract and disorient people in order to lead them further and further away from Christ, God's holy angels are “ministering spirits sent to serve those who will inherit salvation” (Hebrews 1:14). Angels and demons are invisible to the human eye, unless of course they choose to visibly appear, such as when two holy angels appeared at Christ's empty tomb. They asked Mary, “Woman, why are you crying?” (John 20:13)
Demons fear the risen Savior because the Messiah “triumphed over them by the cross,” (Colossians 2:15) and “was raised on the third day according to the Scriptures” (1 Corinthians 15:4). The fate of every demon is sealed, just like the fate of their master, Satan.