Do I believe in extraterrestrial life? No, but I’m not dogmatic about it. The Bible doesn’t explicitly say there is no life on other planets so I wouldn’t want to speak where it is silent. But there is also no indication that I should be concerned about it.
But it is interesting that so many people who deny God’s existence spend so much time with the topic. Multiply the very low odds that extraterrestrial life exists times the very low odds of us being able to discover it if it did exist times the odds that the life would be able to communicate with us and would not be hostile to us and could help us in some way and you get insanely low odds of making the search for extraterrestrial life a meaningful part of your worldview.
The #1 problem with humanity is sin, and a solution has already been provided. Repent and trust and Jesus and your problem is solved for eternity. Every other path will yield failure.
I think this classic “Get a life!” SNL skit hints at the escapism that seems to be part of the ET crowd. William Shatner shows up just before the 3 minute mark. The rant starts at the 4 minute mark.

