Well lets look at it, Jason, and see which one of us is incorrect. I can tell you now that the verse has nothing to do with Christians sinning, it deals, as does the book in large part, with Hebrews under Law who are associated with the Name of Christ. Read Chapter 5 to see his rebuke of their ignorance. In regards to Chapter 10, read the whole chapter. It deals with the issue of remission of sins. Where he is speaking about Christians that are sanctified by Christ, he wakes it clear...there is no more sacrifice for sins. The reason there is no more sacrifice for sins is because just as God promised...sin is forgiven in totality. That is what the Greek conveys, as well as the context.
So I will point out again the contrast between the Covenant of Law (Mosaic Covenant) and the New Covenant being contrasted here, and again say, with absolute confidence based on years of study in Hebrews, that in view are not those who have received the Law of Moses, nor those who have received Christ, The Sacrifice of Christ, the New Covenant, or the Holy Ghost, but those...
...who reject it:
Hebrews 10:26-29
King James Version (KJV)
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 blue is speaking of rejecters of the (Covenant of) Law, and the green is speaking about the rejecters of the New Covenant. These have trodden under foot Christ, counted His Sacrifice unholy (as opposed to the sacrifice of the Law), which means they reject His Sacrifice (which is the only Sacrifice that can save), and have rejected the Spirit of Truth.
That is why, if they sin willfully, "there is no more sacrifice for sins," because they are rejecting the only sacrifice that can save them.
But let's look at this short passage, and thresh it out, rather than jump around.
You exegete the passage and then expound upon what you think the writer is saying.
God bless.