(Yes, this isn't a bit. I don't even know if OC Character fits, but it's the closest I can get for this.)
Far to the west of Japan, long before the Heian era, there was an anomalous sorcerer whose birth shook the balance of the world. In an era when sorcery was largely uncommon, centuries before its foundations as they were understood could even begin to flourish, that man came to wield Cursed Energy.
Jesus only lived for 33 or so years, with no real understanding of Cursed Energy, despite being a sorcerer in and of himself. Despite that, his technique, Salvation, was so tremendously powerful that very few curses, then seen as the agents of the Devil, could even manage to stand near his presence. As such, he was posthumously declared a Special Grade.
The base concept of the technique is that Jesus could cause Cursed Energy around him to multiply against itself and perform RCT. It would become the backbone for many of his miracles, able to cure many grievous wounds and diseases, as well as exorcise curses that had the misfortune of being around the man.
It's said that this gave him a unique understanding of Reverse Cursed Technique, which would become the foundation he could perform miracles with. The concept of a Domain was far before his time, but he managed to create some of the basics. Instead of declaring it with a name, he would begin a prayer to open a Domain without a closed barrier. It would purge the negativity and mildly bend reality to fulfill certain hopes, healing the people who entered it.
After he died, his powerful soul became a minor Vengeful Spirit. After a few days of trying to hold it in, he showed up, using his technique to extinguish himself, but left one final powerful curse that he would one day return.
Source: r/CTsandbox · by /u/discount_mj