Excellent description. Reminds me a little of Richard Dawkins in "The God Delusion," explaining how otherwise useful brain hardware 'misfires' and leads to religious belief.

You mention agency detection as one of the potential modules that misfire to bring about religious belief. I think we can generalize that a little more and say fairly conclusively that the ability to discern cause-and-effect was favored by natural selection, and given limited mental resources, it certainly favored errors where cause was perceived even if there was none, rather than the opposite. In the simplest scenario, imagine hearing a rustling in the bushes: you're better off always assuming there's a cause and checking for predators and enemies. If you wrote it off as nothing, you'd soon be removed from the gene pool.

Relatedly, there is evidence that the parts of the brain responsible for our ability to picture absent or fictional people are the same ones used in religious thought. It's understandable why these were selected for: if you come back to your cave to find it destroyed or stolen, it helps to imagine the neighboring tribe raiding it.

These two mechanisms seem to apply to religion: people see a cause behind the most mundane events, especially rare or unusual events. Of course they disregard the giant sample size of times such events failed to happen, but those are of course less salient. It's a quick hop to imagining an absent/hidden/fictional person -and agent - responsible for causing these events.

Undermining religion on rational grounds must thus begin with destroying the idea that there is necessarily an agent intentionally causing every effect. This should get easier: market economies are famously results of human action, but not of human design - any given result may be the effect of an agent's action, but not necessarily its intended cause. Thus, such results are not fundamentally different from, say, storms: effects of physical causes but with no intent behind them.

It would probably also help to remind people of sample size. I recently heard a story by a religious believer who based her faith on her grandfather's survival in the Korean war, which happened against very high odds. Someone like that must be reminded that many people did not survive similar incidents, and that there is likely no force behind it but random chance, much like, if life is possible on 0.000000001% of planets, and exists on the same percentage of those, given enough planets you will have life.