Alien Invasion

I saw a trailer for the movie "Battle: LA" a couple of days ago. It's about space aliens attacking Earth (again).

Although it looks like it has spectacular visual effects, there is no clue given about alien motivation for the invasion, and I suspect that—as in most alien invasion movies—any reason given will be unrealistic. Maybe they won't give a reason at all. Spielberg's "War of the Worlds" was all the better for not delving into motivation or means. The monsters in that movie were a sudden cataclysm akin to a massive storm or earthquake.

So I was thinking about invading aliens, why they might do it, and how. There are very few scenarios that, in light of the tremendous effort it would take to undertake the conquest of Earth, give a realistic explanation as to why creatures from another planet would try it. But just a few minutes ago I thought of a good one which I had not considered before: to save our souls.

How is this for a great scifi premise: An alien race detects our presence and realizes that we have an intelligence similar to their own, but we're not quite as technologically advanced. These aliens are also very religious.

After a brief period of studying our culture, missionaries arrive. They might not even be very representative of the entire alien species; they might be relatively poorly equipped and underfunded due to a lack of support at home. But they are determined to save us, even if they have to kill us to do so.

There could be several religious factions, just to make it more interesting. One group establishes a stronghold on a floating platform in the Pacific Ocean and takes over most of our airwaves for religious broadcasting, but they are relatively peaceful until earth religious groups attack them. Another fringe alien group destroys Rome and installs their own alien Pope, thinking that they can just take over and convert Roman Catholics that way. Individual aliens establish compounds to preach their own versions of the truth, and look for ways to control human minds in order to reach more converts.

I think this premise is great, and more believable than most. I'm sure I'm far from the first person to think of it, but it's novel to me.