Unjust religious afterlives

The Aztecs did not believe your fate was based on whether or not you lived a moral life. Instead, they believed that whichever of the three afterlives you got depended largely on your role in society and the manner of your death. So you could be a total shit who spent their adult life breaking into blind people's houses to move their furniture around, and depending on how you died, you could still find yourself sitting by the side of some god in the late afternoon sun, eating cheese and drinking wine with your feet in the pool.

To end up in the hellish realm of Mictlan, you had to die either from old age or from a disease (with a couple of exceptions). So, if your syphilitic Grandpa kicked the bucket, he'd be cremated along with a dog, which would serve as his guide along the dangerous, treacherous, four-year path to Mictlan.