I'm not a fan of syncretism either. While Halloween was implemented as a means of Christianizing pagan holidays in an attempt to evangelize pagans, I think the way that they chose to do so is horribly misguided.
Doing something on the same day as a pagan holiday makes sense. It's providing a Christian alternative. Dr. Robert Bennett goes into detail on how the Malagasy Lutheran Church in Madagascar sets up events during the local Animist festivals in his book I Am Not Afraid: Demon Possession and Spiritual Warfare.
The big difference here, is that the Christian events the Lutheran church does in Madagascar draw no content from the pagan festivals. They allow for no overlap and no creeping in of paganism. In fact, they do the exact opposite, incorporating "exorcism of place" prayers which often result in the manifestation and expulsion of demons from the non-Christians in the audience. Halloween, on the other hand, incorporates many pagan ideas, including seeking to communicate with the spirits of the dead.
Because they are the only denomination with a specialized group that focuses on exorcisms. There are even roman catholics priests that think having exorcists is unneccessary or even suprised they still exist
In Eastern Orthodoxy any priest is considered an exorcist. And if it doesn't work with a normal priest they take them to monasteries.
There are also Lutheran and Anglican books on exorcism. Lutheran churches in Africa actually receive the most converts and members by doing exorcism services. Individuals and families suffer from spiritual oppression and they seek the Lutheran Church to exorcise the demons and protect them.
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