The entry for Karesuando in the guide book mentioned a preacher of whom I have never heard, so being a clergyman myself I thought I ought to make some enquiries. The Tourist Office turned out to know rather more than I expected, for the man behind the desk was a lineal descendant of one of the leaders in the Laestadian Revival!
Unfortunately his English was not the best we encountered in Scandinavia and as a result I got the order of events slightly wrong - you can look Lars Levi Laestadius up on Wikipedia for the correct version. Although it seems that Laestadius was something of a puritan - not my favourite manifestation of Christianity - at least he stopped the Laps stealing each other's reindeer!
The Laestadian movement is still flourishing today and, as the gentleman said, "The work of God will go toward all the time" - he meant, "forward".