
I've seen the ads for the Alpha Course, and I've watched Jon Ronson's TV documentary. A few years ago I also saw several of the David Frost TV series "Alpha: Will it Change Their Lives?" and its more recent follow up: "Alpha: Did it Change Their Lives?" The David Frost series featured clips from the Alpha Course led by Nicky Gumbel at Holy Trinity Brompton. Apparently the satellite courses make extensive use of videos of Nicky Gumbel's sermons (if sermon is the right word), though they are free to adapt.
I got the impression from the David Frost series that the course is intended for teetering agnostics, and is unlikely to sway those who self-identify as atheists. There was nothing I heard in the Nicky Gumbel clips, or saw in any of the documentaries, to suggest that they are using anything other than small group dynamics to encourage people to share and discuss hitherto private thoughts about belief. To be honest, I found it unimpressive. The fact that they are promoting glossolalia suggests that the whole enterprise is geared towards emotional response and "personal experience of the Holy Spirit" rather than addressing annoying factors like reason and evidence.
Adam Rutherford's experience seems to bear out my suspicions, though he identified an additional concern that I don't recall surfacing in the documentaries. The Alpha Course, he says, is a homophobic cult. He puts it that strongly, despite finding Nicky Gumbel himself to be a thoroughly nice chap.