[kstenerud]

It stems from the human desire for an ultimately ordered world that also allows us some agency (because evolution wires us to maximize our security). Such a thing is impossible without a godlike force that imposes order (or at least will eventually impose order) and also provides a path through human agency to reach a state of "everything's going to be okay forever".

The desire can become so great (especially during times of insecurity or trauma) that people will start imagining that such a being/beings/force exists, and has offered them agency and a path.

Such beliefs are actually evolutionarily useful because they can counter the despair that can creep in during stressful times, giving believers a survival edge. They can also foster social cohesion, another survival edge.