After living in North Carolina for ten years, I think I get a lot of my inspiration for these comic from the Southern Baptists. Not that they are better/worse than any other religion, just more of the fact that you cannot escape religion in the south.
I thought of this one though based on the idea of 'being saved.' When I asked my friend what that meant, as it is not a Catholic concept that I was brought up with, he explained along the lines of a get out of jail free kind of thing (i.e. We sin, everyone knows it, but we love God and so we go to Heaven).
So, the idea of a person who knows they are sinning, dying and realizing they were, in fact, accountable for their actions seemed somewhat funny to me.