The problem I have with the original post is that the viewpoint is purely philosophical.
In other words....regardless of what scripture presents as truth regarding the security of the believer, you have a philosophical problem with how you think it plays out.
However, you may not be aware that there is a difference between "Eternal Security" and "Once Saved Always Saved"
Eternal Security is the scriptural teaching that once a person believes in Christ, there is nothing he or she can do to forfeit eternal life. This teaching recognizes the power of the gospel, the unconditional grace of God toward the believer, the redemptive work of Christ, and indwelling and sealing of the believer.
Once Saved Always Saved, however, teaches no such unconditional element. It is a doctrine of works, whereby it is taught that real Christians behave a certain way, evidenced by "fruit". It hangs on the out-of-context use of verses such as Philippians 1:6, "He who began a good work in you...". This teaching in no way leaves room for someone to abuse the grace of God, because that would be so-called "evidence" that he/she was never born again to begin with. So it is not actually Once Saved Always Saved. Instead, it is "Once Saved Always Working". This works based notion of eternal security is no security at all, because it gives ammunition to the self appointed fruit inspectors who are always running around pointing at who's not saved (at least in their opinion). It is conditional security in the same exact fashion as the doctrine which says a believer can forfeit his eternal life. One says you lost it, one says you never had it, and both agree that works are the key to maintaining assurance.
And I have a problem with the philosophical rebuttals like, "think about it this way..."
We don't have to resort to philosophical meandering, because scripture declares that the believer is secure:
He who believes upon Jesus Christ has eternal life and shall never come into condemnation, for he has passed from death to life (John 5:24).
Jesus Christ, by His blood, has forever perfected those who draw near (Hebrews 10:1, 10, 14)
We have become partakers of the divine nature (2Peter 1:4)
and have been sealed unto the day of redemption (Ephesians 4:30).
It is finished