What you portray in your fictional world can be a reflection of how you perceive the world at large but not necessarily be a reflection your own moral (or otherwise) viewpoint. To focus on the minutiae of an aspect of human life and then bore down to the very heart of a subject, involves rigor and the ability to bring back from the abyss what you have witnessed in a way that your evidence can be shared without becoming part of you. The old Nietzschean adage may best apply here ("when you gaze into the abyss..."). Obviously, you can not wade through oceans of blood without staining your clothes but you can look and relay, while standing on a hill above said ocean. Fictional worlds can be created without recourse to your own views and values via the use of imagination - imagining someone with antithetical (to your own) moral, spiritual and philosophical values on the page is achievable without betraying your own views in that the character can be created deliberately - with recourse to technique or in response to a work not of your own etc.
I watched a documentary on Timothy McVeigh last night and how he was apparently inspired to blow up the federal building after reading the infamous 'Turner Diaries' - it got me to thinking about my own work and whether it might inspire someone to imitate something I've written about. I realized that because it is fiction, even though what I write is largely idea-sourced from true events, it is ultimately from my imagination and, yes, it has been filtered through my own experience and mental processes but yet, it is not something I condone or that I believe in. I write about taboo subjects and horrific things at times, but I do it deliberately and consciously, knowing full well that what I put on the page can influence others (perhaps) and that readers (especially close friends etc) may see something of myself amongst the words. Yet, I also know that I have to be careful not to let myself bleed on the page lest it becomes apparent that my involvement in the story is in a greater capacity than that of author.
At the end of the day it doesn't matter how objectively we write our fiction, it is friends and family who will always be our harshest judges/critics and see things in the words where there is nothing to see. Like McVeigh, there will always be people who interpret your work through their own filters and misconceptions about the author's intentions and/or experiential involvement in their fictional worlds. As long as the horror is carried out on the page and not in the real world, then the author's lot remains an honorable one and the transcribing of such horrors an outwardly cathartic experience (for the author at least). Perhaps, it is the reader who brings the most amount of subjective (moral, philosophical, spiritual etc) baggage to the experience of reading a fictional work. Perhaps, it is the reader who needs to question themselves and how they interpret a work of fiction. After all, the difference between what one reads and what is actually written can be poles apart. And then there is poetry . . .