Like Fred, I have been looking in on this thread loosely from time to time and I would have to agree with Fred in that your thinking about what salvation really is lacks depth. The only reasonable explanation for the situations you sight is not that they were saved, but that they thought they were, which is presumption.
I would add to Freds points the following. Just as it was rediculous for Nicodemus to ask the question "how can a man enter a second time into his mothers womb and be born (physically) again?", it is rediculous to suppose you can be unborn (spiritually) again. Once the Holy Spirit gives spiritual life to the soul it doesn't die again, because that life, and the sustenance of it, is based on God's will and power and satisfaction of sin. If you read the scripture you will also see that that person doesn't drift off and commit sin as you say for John tells us in his first epistle that that new life prevents the continual habitual, practice of sin:
"1Jn3:9 Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God. 3:10 In this the children of God are manifest, and the children of the devil: whosoever doeth not righteousness is not of God, neither he that loveth not his brother."
John is emphatic here, so that while a believer may backslide for a while he can't go on this way, he will be chastised, as per legitimate sons in Hebrews and repent, not just drift in and out. Your problem is that you are not exegeting according to the analogy of the faith, that is putting all the applicable scriptures TOGETHER TO COME UP WITH YOUR DOCTRINE. This piecemeal eisegesis will always lead to the error you exhibit. Not even discussed here is the issue of an internal struggle with sin in the true believer as Paul speaks of in Rom 7. Any time someone tells me that Romans 7 is about a preconversion experience of Paul, I must say that I doubt the reality of their conversion. One of the primary marks of the new birth is a growing awarness of one's sinfulness and an hatred for it, and that hatred is based on the "flesh lusting against the spirit and the spirit lusting against the flesh". This is spiritual warfare and those who know nothing of this are most likely either very young in the faith or not yet converted. A tender conscience in the 'fear of God" is one of many key signs of the new birth, new spiritual life in the soul.
Can a man be unborn again? I don't think so, so may I suggest that you rethink those scriptures, especially since if you dig deep enough they will lead you to reconsider the sin of Presumption which Ps 19 calls "the great transgression".
