In the context of a conversation about the challenge and difficulty of being a follower of Jesus, and hence the shallowness (and untruth) of a fluffy nice "become a Christian and all is lovely" type invitation, I was told this story.
One of the group recounted how when his son had been 14 he had been invited to a local Crusader group by a school friend and was keen to go. Prior to him attending though, the dad (who was recounting this story) received a phone call from the school friends' dad. The call was to check he was happy with his son going to the group, this wasn't a warning off it was a warning of the implications ..... did he realise this was "dangerous stuff" and his son was really really welcome but it was a place that took faith seriously and his son could end up a missionary, a vicar or the like!
Loved the confidence and reality of this. It also has a wonderful footnote in that the son did go to the group AND is in fact, now a Vicar!