Your verse says that some Jews (Heberws) "received the knowledge of the Truth".
Notice that your HEB verse does not say that these HEBREWS...believed it.... it only says they received it.. (they heard it)....and because they didnt believe The Gospel......"there remains no more JESUS BLOOD to forgive their sin"....which means there is no more sacrifice available for them, because they refused to BELIEVE.
See, Jesus IS The Savior of the World, but His salvation is only given to the BELIEVERS because they BELIEVED it.
"unbelievers"..... have no sacrifice available for them.......is what the verse is showing us.
The verse is showing us that even tho Jesus has died for us all.......His Blood Sacrifice does not save us unless we BELIEVE.
And we see in your Heb verse that they heard the Gospel... they "received it"... but they never believed it., and that is why the Apostle told them that no sacrifice was available to them., as when you reject the sacrifice, then the sacrifice can't help you, can't save you.