It's a fine line... I was raised in the truth so there was nobody really concerned about what I was getting into as I was growing up, I was just the weird kid. I haven't ever caught up with anybody from school to let them know, and if I did make a big deal about it, I think they'd still think I'm weird. With new friends I mention it briefly, sometimes for drama I add that I escaped a cult, but I have rarely gotten a bite. I think that the whole concept of religious discussion makes people uncomfortable, and think about what you're trying to do when you talk about it:
When you were a witness, you were trying to get them to talk about god to recruit them. Now you're trying to get them to talk about something else to encourage them not to join. Either way you're trying to sell them a concept. People don't usually respond to that, they just prefer to let the subject float away. It's just boring.