From Kevin DeYoung's forthcoming book, The Hole in Our Holiness: Filling the Gap Between Gospel Passion and the Pursuit of Godliness (Crossway; August 31, 2012), page 123:
We must always remember that in seeking after holiness we are not so much seeking after a thing as we are seeking a person. The blessings of the gospel — election, justification, sanctification, glorification, and all the rest — have been deposited in no other treasury but Christ. We don’t just want holiness. We want the Holy One in whom we have been counted holy and are now being made holy. To run hard after holiness is another way of running hard after God. Just as a once-for-all, objective justification leads to a slow-growth, subjective sanctification, so our unchanging union with Christ leads to an ever-increasing communion with Christ.