A couple more comments: the title is misleading because before reading the parable it sounds like it was composed by an unbeliever. Also, some of the earlier posters had it right -- God will not give up on the outsiders, but when the banquet is over He will, with great resignation, consign them in perpetuity to a place outside the banquet hall.
You can also stress the notion that all they have to do is choose the correct door and they are admitted, and that it is their poor choice that makes them so hapless.