Easy, in most religions (not All) you have a reflecting period to judge weather you were just in your life and lived it to the best you could, or if were you were waste of human skin (Judgment Day) and go on to hell (if you believe in it) for the way you led your life.
After flatlining for 4 minutes the last time I was in the hospital, it kind of changed the way I see things in life and feel about the after life.
Kind of like the saying "hind sight is always 20/20."
It also happened to be a kick ass line that a ghost of a corrupt cop used in a movie, talking about his life and where it went wrong.
It's taken form "Batman Dead End" it is an enhanced version of the jokers face.
In my belief you have see your life (kind of like a movie) and you are judged for what they saw and felt was in your heart at the time of your actions. So you get a flashback showing of your life's greatest and worst and then they weigh the two to get the outcome of your life and merits, and to deem if you go on to a better place or to a bad place for the rest of your after life.