Herman Bavinck in Reformed Dogmatics:
Christ is our holiness in the same sense in which he is our righteousness. He is a complete and all-sufficient Savior. He does not accomplish his work halfway but saves us really and completely. He does not rest until, after pronouncing his acquittal in our conscience, he has also imparted full holiness and glory to us.
By his righteousness, accordingly, he does not just restore us to the state of the just who will go scot-free in the judgment of God, in order then to leave us to ourselves to reform ourselves after God’s image and to merit eternal life. But Christ has accomplished everything. He bore for us the guilt and punishment of sin, placed himself under the law to secure eternal life for us, and then arose from the grave to communicate himself to us in all his fullness for both our righteousness and sanctification (1 Cor. 1:30). The holiness that must completely become ours therefore fully awaits us in Christ.