Sanctification is not a repair job

Sanctification is not a repair job. God is after something new.

...

But is there not such a thing as growth in sanctification?, progress in the Christian life? ... There is a kind of growth and progress, but it is growth in "grace", a growth in coming to be captivated more and more by the totality and the unconditionality of the grace of God. It is a matter of getting used to the fact that if we are to be saved, it will have to be by grace alone.

We should make no mistake about it: sin is to be conquered and expelled. But if we see that sin is the total state of standing against the unconditional grace and goodness of God, if sin is our very incredulity, unbelief, mistrust, and insistence on falling back on our self to maintain control, then it is only through the total grace of God that sin comes under attack, and only through faith in that total grace that sin is defeated. To repeat: sin is not defeated by a repair job, but by dying and being raised new.

--Gerhard Forde
(from his essay, "A Lutheran View of Sanctification")

Subduing sin - is that where peace is found?

It is neither the tyranny, nor the troublesomeness of sin in a believer, that doth eclipse the beauty of Christ, or the favor of God to the soul. Our standing is not founded upon the subduing of our sins, but upon that foundation that never fails; and that is Christ himself, upon his faithfulness and truth.

...Though there be ebbings and flowings of the outward man, nay, of the inward man, in the business of sanctification; yet this is certainly true: "That believers are kept by the mighty power of God, through faith, unto salvation." They are kept in holiness, sincerity, simplicity of heart; but all this hath nothing to do with the peace of his soul, and the salvation and justification thereof: Christ is he that justifies the ungodly; Christ is he that is the peace-maker; and as Christ is the peace-maker, so all this peace depends upon Christ alone. Beloved, if you will fetch your peace from any thing in the world but Christ, you will fetch it from where it is not.

...While your acts, in respect of filthiness, proclaim nothing but war, Christ alone, and his blood, proclaim nothing but peace. Therefore, I give this hint by the way, when I speak of the power of Christ subduing sin; because, from the power of it in men, they are apt to think their peace depends upon this subduing of sin. If their sins be subdued, then they may have peace; and if they cannot be subdued, then no peace: fetch peace where it is to be had; let alone subduing sin for peace; let Christ have that which is his due; it is he alone that speaks peace.

--Tobias Crisp (1600–1643),
[The Complete Works of Tobias Crisp (London: 1832), 1:12–14]