Swedish Churches -
Viking sacrificial groves, relics and spirit guardians
Churches plays a large role in the Trolldom tradition. Their importance are linked directly to older customs predating the churches as well as to traditions connected to Christianity. Items of power are collected from them and their surrounding cemetaries (Every Swedish church is surrounded by a cemetery), initiations are conducted there as well as various spells. To give international readers an idea of what Swedish churches are like the 13th century church is Frösön, Sweden is a good example.
On top of a Viking sacrificial grove and the old norse god Frey (Frö)
This tapestry to the left from Överhogdal not far from the church made around 940 shows the local contemporary depiction of the norse world tree of Yggdrasil.
There are a few Viking burial heaps just outside the church.
So this makes the church and its vincinity a suitable place to address the Norse God Frey (Frö) with petitions regarding love, sex and peace or charge talismans and other objects in his name.
The Church Grim - Guardian spirits of the church
When the church was built bats were sacrificed to become the Kyrkogrim or Kyrk-rå - guardian spirits of the church. This custom is far from unusual and cats, rams, calfs, lambs, roosters - all preferably in the color black -have been sacrificed in this manner. And - at least according to legends - humans have been killed when the foundation of new churches were built. The first person to die in the parish is also said t becomme the helper of the grim. Their function is to protect the church and the surrounding cemetary by scaring or harming those who come with malicious intent.The custom of killing something in order for their spirit to become a guardian of something has a very long history in Sweden. In old grave mounds the spirits are often referred to as dragons. In many cases they are said to take shape of various animals - such as dragons, roosters, horses and so on. There are many methods preserved in Trolldom in regards to how one protects oneself from these dragons when going for the buried treasures. Of course this is known as grave robbery in modern days but the methods are still used. For example they were recently used in Ghana by a client of mine who is a professional gold finder. When the English colonialists left Ghana lots of gold were buried and a lot of them are - according to my client - protected by evil spirits.
Relics
So there you go. Swedish churches are quite interesting.
Sources and read more (in Swedish);
Archeological artical concerning the sacrificial grove under the Frösö church:
https://sites.google.com/site/infoartefactartiklar/artikel-06
An article in Swedish about the relic of St Lucy:
http://www.op.se/jamtland/ostersund/det-ar-speciellt-att-fira-lucia-i-froso-kyrka)
About the kyrkogrim and churches who have them:
http://www.skaneshembygdsforbund.se/pdf/handledning_folktro.pdf
https://archive.org/stream/folkloristiskaoc03wikmuoft#page/n5/mode/2up