A companion verse of Heb 10:10 which confirms the saving result of them Christ died for, namely His Sheep, its Heb 10:14

14 For by one offering[His death] he hath perfected for ever them that are sanctified.

Now who are the them that are sanctified ? Look again at Heb 10:10, and how were they sanctified ? Now these by that same means, Christs death are said to be perfected forever ! This includes their Justification before God, a complete cleansing of all the guilt of their sins. And that for ever !