When I'm speaking at some event, or talking with people on the phone, and I tell them about massively growing movements (thousands! hundreds of thousands! millions! in just a few years!), they always ask:
Why? There are no studies on why people ask one of these questions and not the other, but I have my suspicion about the reason. We ask because most Western believers, by default, understand discipleship as a course, as assimilated knowledge - "Teach them what they should know." Moreover, we ask out of a view in which we perceive ourselves as knowing so much. We ask because we already do know, and we believe knowing is important. There is no way for us to feel too bad about the answer. Either:
This question is far more dangerous, if for much the same reason: how would we answer it about ourselves? The statement "a mile wide and an inch deep" can refer to obedience but far more often in context refers to depth of knowledge: "many who know very little about their faith." Given the difference between those who know a lot and do nothing vs. those who have little but work with what they have - I would prefer to be the latter. In the Parable of the Faithful Steward, Jesus would seem to be arguing much the same.