Well, earlier in the film it is established that Cage's son is a believer (his mother is in heaven, of course), which creates some tension between them. Cage's character arc in the movie is going from Godless scientist to believer.
The last scene on Earth has Cage huddled together with his religious family. His…

Maybe I should have been more clear. I could care less about mass graves being filled in service of, say, comedy.