Pieper (3.48) notes that to preach good works and sanctification is by no mean to undo justification. In fact, the only Scriptural way to preach sanctification is to based it upon justification through faith apart from works. In fact, Pieper suggests that if one is reticent to preach good works, he probably does not truly know the Scriptural doctrine of justification by faith.
in urging the members of their churches to become “rich in good works,” pastors should not be deterred from doing this boldly and resolutely, without any fear or faltering, by the thought that this insistence on good works might crowd out of its central position the doctrine of justification without works. Only if one does not know the Scriptural doctrine of justification by faith will he be timid in asking for a multitude of good works. It is therefore impossible to teach a doctrine of sanctification and good works in accord with Scripture without at the same time teaching justification. According to Scripture the only motive for good works is the pure grace of God, which we have experienced in Christ Jesus.