The Razor Darkness of a Starless Night by Alder G Brandon

What if there was a solution to the problem of pain? When failed novelist Edward Ledger, recent widower Michael Smith, and grieving teenager William Davis each decide to open the pages of the forbidden novel The Singing of the Shadows, they discover an ancient cult seeking this very thing: an escape from all suffering. However, it comes at an unthinkable cost-universal suicide, the voluntary death of all life. Will they submit to the whims of the cult, or dare oppose the cosmic god that leads it?