In reflecting on Machiavelli's use of the words religious and religion in this passage, my mind wanders to some of the people who started out in this debate but eventually left. Fulcanelli, Fiona, stilicho, SomeAlibi, Bob the Donkey, pilotpadron, capealadin -- these are all posters who found more comfort and community in the bosom of PMF than at JREF. I think they departed because their facts were successfully challenged, leaving them with nothing but their faith.
The essence of faith is that it is based on beliefs and not facts. A religious person is faithful, not fact-ful or proof-ful. No one can prove that God exists, but within the structure of religion, that's okay, because religion is about faith and belief, not facts.
In the same way, no one can prove that Amanda and Raffaele are guilty, but within the structure of the guilt community, that's okay, because their community is also about faith and beliefs, not facts.
So yes, some people do make a religion of their position in this case, but it is not the ones Machiavelli thinks.