Christians who won't admit that the witch-persecutors are *their own* are perpetuating the problem.

Somebody does something monstrous?

- Oh nothing to do with us, they were never Christians to begin with, you can't expect us to have seen it coming or done anything about it, can you?

In this case the pastors of those London African churches *should* have seen it coming. It was well known what the witch-persecuting ideology stood for. As the author of that BBC article pointed out: that murder would not have happened in Kinshasa, because the community is more open and people know what their neighbours are up to. But there's no excuse for them not realizing that London was different and anticipating what their ideology would turn into in a city of isolated flat dwellers with minimal family networks.

I grew up in New Zealand with Seventh Day Adventist neighbours. They seemed a bit stuffy and clannish but not otherwise all that weird. I got to meet some of their network of relatives, some of them missionaries in the Pacific, and read some of their literature. It was rather obsessional about things I couldn't see as very important and a bit preoccupied with impending doom, but they managed to get on with their lives without the millenarian stuff getting in the way.

Now transport the same ideology to a totally isolated community with no outside ideas and information to provide reality checks. You end up with the Branch Davidians - a few hundred people progressively edged into organizing their own apocalypse. They were part of a larger church which had simply washed its hands of them. Nothing to do with us. Not Christians, never were.

BTW Muslims deal with this rather more honestly. Very few advocates of repulsive ideologies with criminal repercussions ever get categorized as ipso facto non-Muslim. They are more often seen as genuine Muslims creating a problem. Which offers a route for some sort of dialogue that you don't get with the Christian response of simply cutting deviant fractions out of the community because they're embarrassing.