Flatliners is a must-see if you have ever asked existential questions to yourself. What happens after we die is one such common question, and that's the main theme of this movie, but there are other moral ones that the movie attempts to answer. The movie forays into the depths of human psyche, albeit in a traditional Christian way.
Five medical students, Nelson Wright (Kiefer Sutherland), Rachel (Julia Roberts), Joe Hurley (William Baldwin), David Labraccio (Kevin Bacon), and Randy Steckle (Oliver Platt) decide to conduct experiments with their own mortality. They put themselves in a "state of death" by artificial means and let the cardiograph become a flat line for a designated amount of time. Each person experiences a thrill that makes the experience worthwhile: after all, it beats the heck out of roller coasters and bungee jumping.
But the group get a bigger thriller than they bargained for when the dead people they encountered during the flat lining session invite themselves into the real world. Billy Mahoney (Joshua Rudoy), a boy Wright had picked on as a kid, is back with a vengeance. Hurley, a womaniser who videotapes his conquests, is attacked by images of girls he has slept with and videotaped without their knowledge. The others have their own guilt trips as well, except that these trips are as real as ever.
Finally, Labraccio decides to make peace with his past, in a Catholic confessional sort of way, and then his visions disappear. The others do the same and all ends up being well.
When I first saw this movie a long time ago, it got me to thinking about life and death. I personally think we rot after we die; i.e., I don't believe there is an afterlife, and certainly not a confession period. The way I looked at the movie was that the near death experiences dredged up memories of the cruelty they had committed to others in their lives, and it was simply those memories playing tricks on the flatliners.
I considered the movie to fall in the psychological horror genre, and the spiritual didn't have much relevance to me. I do however think the movie tells us a lot about how we should live our lives while we're around: with reason. This is evident in the way the students atone for their "crimes". They bear the responsibility and in a couple of cases, and the responsibility isn't too great for most of them. In the case of Hurley, however, the one person who he truly loves leaves him after finding the tapes, and Wright almost dies for real.
More subtly, the movie also brings out the obsession humans have with their own mortality, given that we devise "entertainment" and "recreation" where the thrill arises from the risk of defying death. Flat lining is just an extreme form of such entertainment.
When you die, no one's going to punish you for what you've done (and in any case, the thought of punishment after death should not be a motivator for how you lead your life). You have the freedom to do whatever you want while you're here, but if you want to be happy with that freedom, then don't do anything to others you wouldn't want done to yourself.
Finally, regarding death itself, I think death is a natural consequence of life and not something to be feared or put on a pedestal in any other manner.