Generational curses are biblical.
As for the Knights, didn't Micheal at one point (Grave Peril) basically say: "if you made a deal with that thing of your own freewill I can't help you against it?".
White God and Old Testament God aren't necessarily the same guy. Certainly by the time St. Patrick comes around, that sort of thing isn't going on. And the free will thing is exactly my point, the curse robs someone of their free will a few nights a month and forces them to go around killing people nearby. Further, it really goes against the whole redemption schtick the white god pushes.
Then again, it could be him trying to teach Patrick a lesson about hubris.
Which would make the white god a jerk since his lesson involved getting hundreds or even thousands of people killed over time. Worst lesson ever!
There's no evidence for him being a wizard - not in any legend. Saints, at least those with power, are supposedly picked by god (as opposed to the archangels handing out the swords).
The Catholic Church says they are picked by god, but it's political. Further, when miracles are performed by people saying they are religious, then it is faith and god doing it. When they are done by someone saying they aren't, then it is magic, wizardry, paganism, or whatever else is handy. If Harry said he was doing the white god's work, and managed to cure some diseases and the like, he could probably pretty easily be made a saint by the Catholic Church.
Saying "Well there's no evidence against it so it might be true" is an invalid as talking about all those mailmen that Billy killed. No, there's nothing in the books about him assuming wolf form to chase and eat mailmen, but there's nothing that says he doesn't.
Well, there's certainly evidence he could be a wizard. He cursed that guy. He did magic. We're not talking about someone that didn't do anything.
It serves as a warning - do blah and your line will be cursed to the end times. And I'm not encouraging the creation of them - just pointing out that from my reading of that book it doesn't appear that mortals can either curse them or cure them.
Yeah, because that's a great warning. That's why Harry was so familiar with it. Heck, they don't even know why the guy was cursed. Horrible warning. Further, it's EVIL. A warning that results in a bunch of innocent people dying is evil. Those innocents are dead because of the white god if he was powering that curse, that puts their blood on his hands and there are tons of other ways to handle it.
The MacFinn line probably encountered countless wizards over the years and none of them could end the curse. MacFinn himself had someone construct a three ringed magic circle to contain the beast. Someone built "a cage for demonic demigods and archangels" but couldn't end the curse. If someone could build a cage to keep Jake in (or out) but not in the curse, well, to me that says that only Great Powers could do it.
It isn't easy getting all those shifts and other bits together to end such a curse. Far easier to make those containment circles. We only have evidence they ever encounter ONE real person of any talent (the one that originally made those circles) and we don't even know if they WERE a wizard. Perhaps the containment was the limit of their capability. It's always easier to contain than remove, even in the game. A level 20 block would very easily contain him, whereas you are going to need more like twice those shifts to get rid of the curse (to say nothing of symbolic links).
Anyhow, fundamentally, and back to the original topic more or less, any being that did this curse did a great evil. I don't care what their past accomplishments are or their recommendations. The curse directly results in tons of innoncents dying and other innocents being punished. It's an evil thing. If there's a being that shows up after removing it and that being is upset, then they are defending evil. A warden would have plenty of reason for removing such a curse AND opposing any entity that got upset by it. This also provides plenty of reason to try to deal with it oneself. A powerful being might just pickup the curse and toss it elsewhere if you let them interfere, or they have a price that requires you impede your ability to help others. Contain the beast, spend time studying it and the curse, and figuring out a way to end it is slower and safer.