It really depends what is meant by "the same instinct". The reason I don't agree with the parent comment is because to truly believe in a Boltzmann brain would

It really depends what is meant by "the same instinct". The reason I don't agree with the parent comment is because to truly believe in a Boltzmann brain would seem maximally nihilistic. Many people truly believe in God/gods at their deepest level. While the Boltzmann brain is an interesting thought experiment, I don't think anyone really takes it to heart the same way a Christian believes in Jesus. Even while I would probably give the Boltzman brain a far greater probability than most, people don't go around telling other people this is all just a momentary, random fluctuation.