At the end of the game, depending on how many people you kill, the type of people/animals killed, the type of weapon used, the speed you played through the game, or the difficulty you play the game on, the final score sheet will generate a summary based on how your playthrough meets one of those conditions.

In particular, in regards to how many people you kill, beating the game without killing anybody will give you the summary "Thank you for playing, JESUS.", while beating the game presumably killing everything you can will give you the summary "Congratulations, SATAN.".