Here are the quotes from G. C. Berkouwer that I've mentioned a few times which I've found so helpful in understanding how justification is the engine of sanctification, or how the gospel that "Christ died for our sins" is itself what propels growth in godliness. These are from his book Faith and Sanctification. I confess I wish I had heard more of the newly imported foreign power of the indwelling Spirit as that which gives believers new spiritual taste buds to pant after holiness (Berkouwer interacts with Bavinck on this point on pp. 82-84, and I find Bavinck much more convincing); but this hardly detracts from how meaningful I have found Berkouwer to be on this most practical of questions of Christian growth.
Holiness is never a 'second blessing' placed next to the blessing of justification. . . . Our completion is only realized in Christ (Col 2:10) 'for by one offering he hath perfected forever them that are sanctified' (Heb 10:14). The exhortation which comes to the Church is that it must live in faith out of this fullness; not that it must work for a second blessing, but that it must feed on the first blessing, the forgiveness of sins. The warfare of the Church, according to Scriptural testimony, springs from the demand really to live from this first testimony. (64)
The Reformed Confessions never teach that believers, having gone through the gate of justification, now enter upon a new territory where they must, without outside help, take their sanctification in hand. It is not true that sanctification simply succeeds justification. . . . there is never a stretch along the way of salvation where justification drops out of sight. Genuine sanctification--let it be repeated--stands or falls with this continued orientation toward justification and the remission of sins. (77-78)
The believer's constant 'commerce' with the forgiveness of sins and his continued dependence on it must--both in pastoral counseling and in dogmatic analysis--be laid bare, emphasized, and kept in sight. (84)
The heart of sanctification is the life which feeds on . . . justification. (93)
[A]ny view of regeneration, faith, and sanctification, must be weighed and tested by the criterion of whether it does justice to the forgiveness of sins as the only ground and source of sanctification. (96)
And the last paragraph of the book:
In the bond between faith and sanctification we perceive, no less than in the bond between faith and justification, the pulsebeat of the Gospel. If faith will but lift its blossoms to catch the sunlight of God's grace, the fruit will be a life imbued with holiness. (193)