Heb 10:26,
For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
Heb 10:27,
But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries
Sorry, had a storm pass through last night (it's monsoon season here), so it knocked out my internet.
I responded to the first part of your post already, but to get to the rest...
Hebrews needs to be read in full, rather than pulling out random verses, otherwise you get the wrong context.
If we look at earlier verses too...
Hebrews 10:11-18: "And every priest stands ministering daily and offering repeatedly the same sacrifices,
which can never take away sins. But this Man, after He had offered
one sacrifice for sins forever, sat down at the right hand of God, from that time waiting till His enemies are made His footstool.
For by one offering He has perfected forever those who are being sanctified. But the Holy Spirit also witnesses to us; for after He had said before, “This is the covenant that I will make with them after those days, says the Lord: I will put My laws into their hearts, and in their minds I will write them,” then He adds,
“Their sins and their lawless deeds I will remember no more.” Now where there is remission of these, there is no longer an offering for sin.
Pretty clear here. The old sacrificial system was temporary atonement for sin, it didn't completely cleanse a person, and it still can't. Christ's ONE sacrifice has perfected FOREVER (not temporarily, like the old way) those who are being sanctified. What's more, it says that where there is a remission of sins, there is no longer an offering for sin. So proof right here that when one is forgiven THEY ARE FORGIVEN and their sins no longer remembered.
There is no other offering for sin, except Jesus. When we're forgiven, the slate is wiped clean. Our sins and lawless deeds are remembered no more. Great news!! The blood of Jesus is sufficient... not the blood of animals. When I read this scripture I see the modern day pharisees, like catholic priests giving out their eucharist in the mass, but history does repeat itself, there are many today that reject the sufficiency of Jesus' sacrifice on the cross, since they believe that they must add to His work, when nothing can be added. Therefore they reject Him as being sufficient to save them.
So then let's get to those verses you posted further down the chapter, in light of some of the other verses, to get the correct context...
V26-31: "For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins, but a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries. Anyone who has
rejected Moses’ law dies without mercy on the testimony of two or three witnesses. Of how much worse punishment, do you suppose, will he be thought worthy who has
trampled the Son of God underfoot, counted the blood of the covenant by which he was sanctified a common thing, and insulted the Spirit of grace? For we know Him who said, “Vengeance is Mine, I will repay," says the Lord. And again, “The Lord will judge His people.” It is a fearful thing to fall into the hands of the living God"
Interesting example given, which also shows the connection between those two keywords, as in "rejection" and "trampled" being the same, but "how much worse is the trampling on Jesus!!!"
Do you see how your interpretation of verses 26-31 contradicts the earlier verses?
Clearly V26-31 agrees with the earlier verses, that there is no other sacrifice for sins, but Jesus! In context... for those rejecting Jesus, the only alternative for them is the old sacrificial system, which can never take away sins. This is what it means when it says "there no longer remains a sacrifice for sins, but fiery indignation" because they reject the true way and embrace the other way.
The adversaries... these are not believers. The only ones referred to as adversaries in the scriptures are those who belong to the world. If one isn't a child of God then they are a child of the devil. The scriptures say he is their father and his deeds they do. They belong to the world, hence adversaries (like satan, the adversary), enemies of Christ. These are not God's children, they don't belong to Him.
Judas is a great example of one who had knowledge of the truth, but he lacked the true faith. He was never a believer. Those who hear truth and reject it - there is no other offering for sin, only Jesus!! So then all they can expect from their rejection is eternal punishment, which will devour them as adversaries.
V39 even confirms: "
But we (believers) are not of those who draw back to perdition, but of those who believe to the saving of the soul" - so this then confirms the separation between believers and non believers, since believers do not reject Jesus!! Just further confirmation that v26 is not speaking of believers at all, but rather those who hear the truth (have knowledge of it) and reject it, like Judas did, for example. They may even profess to be christians, but they are not saved. So then if they reject the one true way, which is Jesus, there no longer remains a sacrifice for sins, because there is no other way besides Him, and they reject Him. They've been told they need Jesus to forgive them of their sins, but instead they continue on as sinners, rejecting Him. The only alternative for them is eternal punishment!
The "drawing back to perdition" is not what believers do, as confirmed in v39. Just further confirmation that lines up with other scriptures that speak of those who come out from among us that were not of us, otherwise they would've stayed with us... and that believers endure, but those who fall away were not saved to begin with. But not speaking of backsliding, which is different.