I think there were lots of different underground levels in the research base.
When the soldiers went in, they found an unhelpful scientist (not a priest) on the first level.
They left him there with a soldier whilst other soldiers went to the lower levels.
They were then pursued by some kind of creature.
Can’t find this film anywhere. I only know that the film was NOT called The Devil’s Tomb. It was a film similar to that, though.
Thanks everyone.
Question is closed for new answers.
pori Selected answer as best Jul 15, 2022
one of the “Xtro” series?
https://m.imdb.com/title/tt0100975/
Mike_Marshall Posted new comment Jul 14, 2022
The movie has been identified. It was Alien Lockdown (2004). But thanks for trying to help. I appreciate it. I will watch those xtro movies, though. I like those kind of movies with aliens and experiments etc.