For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit,
5 and have tasted the good word of God and the powers of the age to come,
6 and then have fallen away, it is impossible to renew them again to repentance, [d]since they again crucify to themselves the Son of God and put Him to open shame.
7 For ground that drinks the rain which often [e]falls on it and brings forth vegetation useful to those for whose sake it is also tilled, receives a blessing from God;
8 but if it yields thorns and thistles, it is worthless and close [f]to being cursed, and [g]it ends up being burned.
>>> For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit,
If you quoted this passage as an example of unforgivable sin, I would like to point out a couple of things...
1. “Fallen away” is not a reference to condemnation
2. “Renew again to repentance” is not a reference to salvation.
Those are key operative phrases that can easily be confused with condemnation and salvation, but they are more in line with a person’s state of mind... which is what is being discussed.
My short interpretation of that passage is “Those who turn from the faith (fall away) are vulnerable to an early death.”
Another alternate reading of that passage refers to those who have actually seen the works of the Holy Spirit, and still turned away (refused to accept Jesus). In other words, if the Holy Spirit Himself cannot win a person’s heart to Christ, it is impossible for anyone else to.
Since it is difficult to understand exactly who is being referred to in verse four (saved or unsaved), I would offer both interpretations as possibilities... but I would not say this passage refers to the unpardonable sin.