Consider a man who was raised in a church who teaches once saved always saved, attended services regularly as an adult, regularly professed his trust in Christ, and made an effort to lead a decent, godly life. Such a man is, without hesitation, what every person who believes in Christ would label a Christian. But if he flees with someone’s wife, then all of the evidence is disregarded. Not only is he not faithful now, but he was never faithful in the first place, despite the fact that in the past he did everything that current devoted believers of OSAS will cite as proof of their own conversion!
With that line of thought, how would every other self professed Christian not be considered never saved as well? Is it because they didn’t depart?
If they do depart, then the life they lived before they ever departed (a faithful Christian) would have been one of being never saved. That is a disturbing thought, because that would have every single person at this very moment to have never been saved before they even do depart. The reason why is because all of the others who are considered saved would point to the same evidence of their life to know they are saved, which is the same evidence that they would have pointed to in the past to those who are now considered never saved!!
In total: At this very moment if anyone said so and so were saved…but then they fall away…they were never saved. If they were never saved, then the life they were living (from the beginning of their conversion up until they departed) would be of one that was never saved. This is disturbing.
The ugly reality behind the supposed comfort of the doctrine of once saved always is It's supposed to provide believers with the assurance of salvation, but logically, it does the opposite. Those who live like faithful Christians, who sincerely (to every appearance) describe themselves as being children of God, can still fall away and thereby prove that they were never regenerated/saved at all. To be true and honest with their belief, no person who believes in OSAS would categorize anyone to be saved, as such an individual will prove their salvation to be genuine by dying to the faith.