It could be really interesting. Maybe it would show a character in the Harry Potter universe who is also part of a church community. They might struggle to balance their magical life with their religious beliefs. For example, they could wonder if using magic goes against the teachings of their church.
I'm not sure specifically about a 'Harry Potter Member of the Church' fanfiction. There are countless Harry Potter fanfictions out there, but this combination might be a bit rare. You could try searching on major fanfiction websites like Archive of Our Own or Fanfiction.net using those exact keywords.
Hermione would probably be very interested in learning about the religious aspects of the church. She'd start reading any religious texts available and try to understand how it all fits in with the Muggle world. Ron, on the other hand, might be a bit more uncomfortable. He's used to the wizarding world and all this Muggle religious stuff would seem a bit strange to him.
I recommend "The Medieval Demon Hunter", a fantasy sword and magic novel, to you. This novel was about the Middle Ages under the glory of the church. The protagonist, Li Ang, was a professional who could use demonic power to fight against "demons" and was also a member of the church. His story was full of suspense and depression, making people feel addicted. I hope you like this fairy's recommendation. Muah ~😗
In such a fanfiction, Harry might be a more pious character. He could struggle with the idea of using magic as it might be seen as something not in line with the church's teachings. His friends might also be different. Instead of Ron and Hermione, he could befriend those who share his religious upbringing. And the whole plot against Voldemort could take on a different tone, perhaps with a more spiritual or moral battle rather than just a fight between good and evil magic.
Well, he might be quite confused at first. Churches are not really a part of the wizarding world he's used to. Maybe he'd be looking around in wonder at all the religious symbols and the way people pray.
One more common theme is the struggle against dark forces. Even in fanfiction, the gang members often find themselves up against some form of evil. It could be a new dark wizard or a dark creature. They have to use their wits and magic to overcome these threats. Also, the theme of growing up is present. We see the characters evolving from mischievous students to more responsible young wizards as the story progresses.
In some fanfictions, the values taught in the church could be paralleled with the values in the wizarding world. For instance, concepts like love, forgiveness, and justice are important in both. A fanfiction could explore how a character's upbringing in the church affects their actions and decisions at Hogwarts, like when they face challenges such as dealing with bullies or choosing between right and wrong.
A really cool one is 'Potter's Posse'. In this fanfiction, the gang members are shown to be involved in solving some mysteries within Hogwarts that the teachers are oblivious to. It's a fun read as it has elements of mystery, friendship and magic all intertwined. The characterizations are quite accurate to the original books, which makes it a great read for any Harry Potter fan.
The most obvious difference would be in Harry's values. In the original, he's brought up in a non - religious magical world and his values are shaped by Hogwarts and the wizarding community. In the fanfiction, he'd have religious values instilled by the church. His attitude towards magic would also be different. He might question its morality more.