The problem with the OSAS arguement is that they can not seem to come to grips with the fact that Christians can backslide to such an extreme degree  and even reject Christ. Since it is hard to comprehend that for them they say that they were never saved. That is a dangerous thing to say. If many Christians were not subject to this backslidden nature then we would not have to have all the strong admonishens in the NT re slipping back into sinful lifestyles. But we do because it is an easy thing to do if we are not careful and keep our eyes away from that sort of thing.
 
So be very very careful when you say some one was never saved because of the way they currently live and even die in. If you are honest and have been a Christian for a while you know that this sort of thing happens.