I heard one pastor talk about the parable of the 10 virgins and 5 were ready, while 5 were rejected for not being ready.  He took the parable to mean that about half of people who consider themselves to be Christians are considered to be Christians by Christ.  Sadly, I don't think the number of true Christians are anywhere near half, but only God knows.  I have doubts that even half of regular church attenders are true, born-again Christians, much less all of the people who grew up with Christian parents or grandparents and therefore consider themselves Christians. 

 I think about that sort of thing a lot myself