Does hebrews 10:26 trully mean what it clearly says
Hi believetheword,
You quoted several scripture including Heb 6:3-6 and Heb 12:15-17, all of which support each other.
Another scripture we can add is 2Pet 2:12-22
But these, like natural brute beasts made to be caught and destroyed, speak evil of the things they do not understand, and will utterly perish in their own corruption, and will receive the wages of unrighteousness, as those who count it pleasure to carouse in the daytime.
They are spots and blemishes, carousing in their own deceptions while they feast with you, having eyes full of adultery and that cannot cease from sin, enticing unstable souls. They have a heart trained in covetous practices, and are accursed children. They have forsaken the right way and gone astray, following the way of Balaam the son of Beor, who loved the wages of unrighteousness; but he was rebuked for his iniquity: a dumb donkey speaking with a man’s voice restrained the madness of the prophet. These are wells without water, clouds carried by a tempest, for whom is reserved the blackness of darkness forever.
For when they speak great swelling words of emptiness, they allure through the lusts of the flesh, through lewdness, the ones who have actually escaped from those who live in error. While they promise them liberty, they themselves are slaves of corruption; for by whom a person is overcome, by him also he is brought into bondage. For if, after they have escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ, they are again entangled in them and overcome, the latter end is worse for them than the beginning. For it would have been better for them not to have known the way of righteousness, than having known it, to turn from the holy commandment (to believe on Jesus) delivered to them. But it has happened to them according to the true proverb: “A dog returns to his own vomit,” and, “a sow, having washed, to her wallowing in the mire.”
This is a description of the willful sinner.
They have rejected Christ, after having known him, and turned back to the law to prove their righteousness. These willful sinners even try to lure others away with them.
How does one make themselves a sinner?
Gal 2:18.
For if I build again those things which I destroyed (righteousness by works of the law),
I make myself a transgressor/Sinner
We see many scriptures warning us against turning back to the law to determine righteousness.
Jesus warned to beware the leaven of the pharisees/Sadducees, Matt 16. "Leaven" being their doctrine of righteousness by works of the law, Matt 16:12.
We see a similar warning in Gal 5:9.
A little leaven (doctrine of righteousness by works of the law, Matt 16:12)
leavens the whole lump.
We are to purge out the old leaven, 1Cor 5:7.
We are not even to associate with such people as they're spiritual fornicators who are fornicating with Hagar (righteousness by works of the law, Gal 4:24).
1Cor 5:9
I wrote unto you in an epistle not to company with fornicators:
1Cor 5:13
Therefore put away from among yourselves that wicked person.
God's will is our sanctification and that we abstain from fornication (with Hagar).
1Thess 4:3
For this is the will of God, even your sanctification, that ye should abstain from fornication:
To fornicate with Hagar (righteousness by works of the law, Gal 4:24), after having known Christ, then this is willful sin from which there is no way for repentance.
Hence why we see scripture saying we should exhort each other (Heb 3:13

to continue to
believe on Jesus and not be lured by the lusts of the flesh to fornicate with Hagar/return to the law for righteousness (which is unbelief, the sin the world is convicted of, John 16:9).