A thought experiment developed to counter undue optimism - not just the sort due to explicit theology, but any sense that events and outcomes in our world are more destined, more proportionate, or more meaningful than we have a right to expect.
The thought experiment takes place in a simulated universe such as Conway's Game of Life, but with an overall benevolent God actually present to prevent sufficiently awful things from happening. The thought experiment then consists of asking what would happen if we asked the mathematical question of what would happen according to the standard Life rules given certain initial conditions - so that even God cannot control the answer to the question; although, of course, God always intervenes in the actual Life universe.
The point of the thought experiment is to contrast our intuitions of a supervised universe and an unsupervised universe side-by-side - since the habits of thought associated with a "supervised universe" may carry over past explicit theology.
Example: Would the twentieth century have gone differently, if Klara Pölzl and Alois Hitler had made love one hour earlier, and a different sperm fertilized the egg, on the night that Adolf Hitler was conceived? For so many lives to turn on such a small event seems disproportionate, and a supervised universe would be run according to a plan in which things happened for sensible, proportionate reasons; such a small and insensible event would not have such a large influence on the sensible reasons of the plan. It's possible to believe in a divine scheme of things without believing in God (e.g. Karl Marx) but such reasoning belongs to supervised universes rather than unsupervised ones.