You need to read to context of verse 5, which is verse 4.
You need to read this......a few times..
Paul preaching to Hebrews.
The Epistle : to the Hebrews.
Paul does it again in Acts 28, the last 10 verses.
SAME HEBREWS, SAME UNBELIEVING JEWS..
In both cases they "trod underfoot the blood of Jesus", "Crucifying Him afresh".
So, how do you crucify Jesus, AFRESH, as in.....if He is right in front of you?
How?
The same way their elders did.......THEY REJECTED THEIR MESSIAH and hung Him up on the Nails.
See, it was not the Romans, it was their SIN OF UNBELIEF that Crucified Jesus TO THAT CROSS.
THAT IS HOW YOU "WILLFULLY SIN".
That is what these Unbelieving JEWS were doing in your verses, after Paul had let them taste the Heavenly GIFT.
And what is that gift, Ms Gift Chaser?
Its the "signs of an Apostle"....>Paul showed them SIGNS. = the heavenly GIFT.
'"""Signs are for the JEWS""""....... Paul is an Apostle. He is showing them SIGNS,.
Signs are from HEAVEN.
All GIFTS come down from HEAVEN, including the 9 spiritual gifts and also the "Signs of an APOSTLE".
Paul is preaching the Cross to these Hebrews, and they are denying their Messiah, same as their elders did, and that is how you CRUCIFY CHRIST AGAIN......you REJECT HIM..."Afresh"...
Christ REJECTION.... is to NAIL JESUS UP on the NAILS OF UNBELIEF.
Understand yet?
That is how you "trod underfood the Blood"..... that is how you "willfully sin" a sin that can't be FORGIVEN,.... as if you deny the Sacrifice of Jesus, then "there is no more sacrifice available to you for your SIN"< CHRIST REJECTOR..... as Paul is telling these hateful Christ Rejecting HEBREWS.