"I challange any athiest or agnostic to complete the Alpha course and not change their thinking." I think that depends on your frame of mind when you attend, and where you are on the spectrum of believer-unbeliever. Some agnostics, who are, by definition, not sure where they stand, might well change their thinking, however if the same people went to a similar course run by Richard Dawkins style atheiests might change in the opposite direction.