I just realized not many people know that godparent doesn't just mean "people who take you when your parents die". While used that way at times, you can just put who gets your kids in your will. A godparent is a role in Christianity that is about who is supposed to be involved with your child's relationship to Christ. So would be funny, with how much we flanderize Sirius as all pranks, if there was a fic in which Sirius was very...serous, about Harry's faith.

I am aware this premise isn't for everyone, and you can headcanon whatever religion for Harry. But the books do heavily point to a Wizarding World that is Christian, despite the Fandom loving some basatardized Wiccan "old ways"(wicca is less than a 100 years old btw)