You know, most people like these elves who decided on sacrificing others can't be reasoned no matter what, even if the spirit or God they are worshipping disagreed with them. They are what we call extremists. They always believe that they are right, they cannot be wrong no matter what even when it's proven to them that they actually are, and if someone is disagreeing with them, it means that that someone is evil.
For the record, these extremists are not specifically religious or religion-related. They can also be atheists, LGBTQ-related, or even Nationalist-patriotic people.
My advice is this: steer yourselves and your family clear of them. Don't make any contact with them, don't look at them in the eye, and off them when they start harming you and people precious to you. Remember, they cannot be reasoned with no matter what.