I don't understand the potential anxiety around aliens for Christians.

Aliens or no, it wouldn't surprise me either way. And the world is a spooky place, made up of far more than matter and energy. What we think we know should be held in a loose grip. God is big enough to contain some "shocking" disclosure.

Literature already exists exploring possibilities. None of this is new.

C.S. Lewis explored the idea of aliens inside a Christological theological framework back in the 1940s.

A modern series, The Sun Eater, plays with similar ideas and possibilities. Gene Wolfe did interesting things in the 80s.

It should be fun to imagine the possibilities of an infinitely creative God, not anxiety-inducing.

Maybe more pastors should read science fiction. Good science fiction, of course.