I was raised in a faith that accepted, even taught, that there are 'unfallen worlds' whose inhabitants never sinned. These residents of other worlds never needed the plan of salvation and Christianity because they had never broken communion with God, so I was told. That there could be diversity of opinion, of religion, or diversity of any kind actually, on distant planets probably never occurred to the elders of the religion in which I was instructed.

So you'd like to see something like the robot Gort show up to announce the arrival of our new religious leader, Klaatu, who in this scenario has superior technology and disarms the planet and then demands our worship? If that were the case, I'd find myself fighting alongside the religionist against these oppressors.

God created the aliens and let them come to Earth already. Have you not seen the movie Men in Black with Will Smith and Tommie Lee Jones?

Ephesians 2:19 So then you are no longer strangers and aliens, but you are fellow citizens with the saints and members of the household of God,