Various religions rely on a calculation of how good or bad you have been when deciding your fate after death.
Depending on the religion it could be that the calculation determines whether you go to Heaven or Hell or alternatively what you are born as in a future life on Earth.
Assume that each religion has its own Gods or lack thereof and that there is not necessarily a single omniscient being.
Let us look at a religion where there is no omniscient being - for example a particular form of Buddhism that believes in rebirth. Your Karma determines whether your next life is as a bug or another human, etc. etc.
In the early days when human population was small, each person could be allocated their own angel/spirit to keep track of their Karma.
These days a better method is needed. There simply aren't enough angels to allocate one per human so what can be done?
Please assume the form of religion that I have described actually exists.
Edit - The ultimate aim of such religions is to escape the wheel of reincarnation. As a human you have the opportunity to get promoted in your next life and do better and eventually escape the wheel altogether. By getting turned into a bug you get sent back down the chain and have to work your way back up again. The good part of this is that bugs aren't sentient enough to commit sins so they will automatically get promoted when they die.