Found this article. Makes a good case from Hebrews 10, the verse and passage that was discussed earlier:
https://eternalcall.com/once-saved-always-saved/3-passages-that-contradict-once-saved-always-saved/
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Hebrews 10:26-29
This passage is very strong objection against the false doctrine of Once Saved Always Saved and is contained in chapter 10 of the book of Hebrews. Let’s look at that passage:
Hebrews 10:26-29
26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
27 But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
28 He that despised Moses’ law died without mercy under two or three witnesses:
29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
The
central intended message of the author is to warn from backsliding wilfully into a lifestyle of sin and from the consequences of such a fall in verses 27 and 29. This passage of scripture is packed with terms designating brethren who are already born again and on the way of salvation.
Notice the terms we already discussed above in verse 26. The author mentions sinning willfully after coming to the
knowledge of the truth
. Jesus Himself is that Truth as He Himself said:
John 14:6 – Jesus saith unto him,
I am the way,
the truth, and the life: no man cometh unto the Father, but by me.
As we have shown previously the term “knowing Christ” is used to design believers in a close fellowship with Christ through the fellowship of the Spirit.
Then the author mentions the consequences of falling away. He says that sinning willfully and deliberately will remove the once for all sacrifice of Christ on the cross and then there will remain no more sacrifice for sins but a
certain fearful looking for judgment.
Verse 29 is the pinnacle of the passage and completely goes against the doctrine of OSAS. The author shows that insulting the Spirit of grace is
worse than disobeying the Law of Moses of the Old Covenant. By so doing, the backslidden Christian is said to have deliberately chosen to
trod under foot the Son of God. How can one do that unless they had access to the Son of God? One cannot put the Son under their feet or insult the Spirit of Grace unless they have Him.
The reborn brother who backslides deliberately is also counting the blood of the covenant by which he (the brother) was
sanctified, an unholy thing. Sanctification is a process that is a work of the indwelling of the Holy Spirit as we have also shown.
In light of the whole passage, it is clear that one
can lose their salvation
after being born again."