Heb 10:14 By one offering he hath perfected for ever
Heb 10:14 By one offering he hath perfected for ever, which includes the doing away with unbelief !
The religious teachers, many of them teach that Christ did not die for the sin of unbelief, but that is another lie. If Christ did not die for that sin, and believing in Christ is something man does apart from Christ's satisfying God's law and Justice on our behalf for our sins, then we are saved by something we did apart from the atonement of Christ's satisfaction, if its true that Christ did not die for unbelief !
However, the sin of unbelief along with all other sins have been paid for by Christ's Death for all whom He died, and they are before God's Law and Justice perfected forever !
For unbelief did not prevent Paul from being saved by Christ's Death from His Testimony here 1 Tim 1:12-16
12 And I thank Christ Jesus our Lord, who hath enabled me, for that he counted me faithful, putting me into the ministry;
13 Who was before a blasphemer, and a persecutor, and injurious: but I obtained mercy, because I did it ignorantly in unbelief.
14 And the grace of our Lord was exceeding abundant with faith and love which is in Christ Jesus.
15 This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners; of whom I am chief.
16 Howbeit for this cause I obtained mercy, that in me first Jesus Christ might shew forth all longsuffering, for a pattern to them which should hereafter believe on him to life everlasting.
Paul testifies to the Grace of God saving Him out of and in spite of His Ignorance and Unbelief, which all of God's Elect are in at first Rom 11:32
32 For God hath concluded them all[The Elect] in unbelief, that he might have mercy upon all.
But back to Heb 10:14, by His Death [alone] He hath perfected [perfect passive participle] forever all whom are being sanctified, that are in a sanctified state ! This means that everyone Christ died for, that even though as others by nature, they are children of wrath, nevertheless unlike them, they are at the same time in a state of sanctification by Christ's Blood Heb 10:10, for the passover Lamb has been slain for them. They are all like Jeremiah 1:5 He was sanctified before he came out of his Mothers womb by the Purpose of God, but that said, he was still born like other men of his day, by nature a child of wrath, a sinner, and needed to be experientially reconciled to God like this Col 1:21
21 And you, that were sometime alienated and enemies in your mind by wicked works, yet now hath he reconciled !
All of God's Elect will experience this reconciliation because of the perfection of the Death of Christ which this is the fruit of !