Arcanist Angus
Well most of the "cunning folk" used a Christian mythos to "blend in" as I see it.
I think there's a big misunderstanding about the nature of Christianity in mediaeval and early Renaissance England. Not just you, Angus, I mean generally. In the towns and cities it was your general Catholicism, but most people didn't live in towns and cities. Most people lived in villages and rural areas. And they practised "popular religion".
This was up until the Reformation when there was something of an overhaul (and more people moving to the towns) and religion became more standardised. But until then, they practised Christianity not so much alongside their folk beliefs, but as a sort of syncretism. They saw no contradiction. They were concerned with what they needed, with sowing and the harvest etc, rather than with what was orthodoxy and what wasn't. They weren't literate for the most part. It's not like they were deliberately trying to retain folk beliefs; by this point there was no distinction made. Like the concept of "sin eaters", and putting wool in a shepherd's coffin to let god know why he hadn't been in church on sunday.
So they wouldn't have "used" Christianity to "blend in". They were Christian. Essentially they were no different to anyone else in their areas.
What we need to do is define "witchcraft" as
they used it - they wouldn't have described themselves as witches - and as we use it, and acertain whether they were witches as we think of them today.