Final Words
Do I think any one of these approaches is any better than the other? No, that would be, quite frankly, absurd. I have not consumed the totality of Harry Potter fanfiction, I cannot cast a qualitative judgment on Pureblood Culture. I have seen it applied well, I have seen it applied in ways that are tonally discordant with the greater work.
I believe these are all neutral tools. The approaches of Pureblood culture, the concept of Wizarding Christianity, or some other wizarding variant of another religion. They are all means by which to tell a story, and there is no one truechoice beyond what you believe will work best for the story you wish to tell.
It is my hope that by gaining a deeper understanding of the real-world background that forms Pureblood Culture, and a better understanding of how religion intersects with witchcraft, you are more easily able to decide which approach works best for your story.
I have listed all works, and sources, I have used, so as to allow research for your own approaches, or if one wishes to simply gain a more nuanced understanding than a meta-analysis of a fanfiction trope can give.