In this context, peoples' beliefs, or disbeliefs, becomes possibly harmful to someone else when they feel compelled to assert the superiority of their atheist/materialist view. I have seen them troll stories to do so. I got into a fight with one last year because I felt he was doing exactly what you say here makes it worthy of getting involved. As I wrote in my story about this, https://medium.com/know-thyself-heal-thyself/pity-the-fools-c8c076c23015 subtitled "Tanka ode to odiferous misanthropic materialists," "What if there is a writer or commenter who has just lost the love of their life and the belief in souls is the only thing holding this fragile person together? This passive aggressively bullying materialist could unapologetically shatter this grieving mourner."