The Barna book sounds like yet another example of conceiving reformation of the church as being about restoring the church to its original, pristine, just-left-the-first-century-showroom condition.

I once heard a very interesting (if somewhat provocative) lecture by Prof. Ron Feuerhahn on “The Uniqueness of the Lutheran Reformation” in which he argued that this represented a “law” approach to reformation (that is, concerned with what we are to do or not to do), as opposed to a “gospel” approach to reformation (that is, concerned with ensuring that what God has done is proclaimed clearly).

He argued that those who seek to correct the church’s moral failings and produce a “pure” church were:

...looking to the Law rather than to the Gospel. We need rather to look at the Gospel. It is not about what we are to do to purify the church (Law), but about bringing the Gospel to the church as she is.

He also included a great quote from Luther:

Doctrine and life are to be distinguished. Life is as bad among us as among the papists. Hence we do not fight and damn them because of their bad lives. Wyclif and Hus, who fought over the moral quality of life, failed to understand this … When the Word of God remains pure, even if the quality of life fails us, life is placed in a position to be what it ought to be. That is why everything hinges on the purity of the Word. I have succeeded only if I have taught correctly.