As someone who likes to think of myself as a Pietist and even (others will have to judge to what extent this is true) an expert on Pietism, I have been asked by several people what I think of that claim.
First, it’s essential to make a distinction between Pietism as a movement and pietism as an ethos. The ethos can exist where the movement no longer does or never did.
As a movement, Pietism was launched by the ministries of Philip Jakob Spener, August Hermann Francke and their (mostly) Lutheran colleagues in Germany in the late 17th and early 18th centuries. It spread to most of Protestant Europe and North America and through Moravian missions to India, Central America and eventually most of the world.
Only remnants of the original Pietist movement still exist–in denominations and organizations that identify themselves with the Pietist movement historically and theologically. For example, The Moravian Church and the Evangelical Covenant Church of America. I would say the Renovare organization is a contemporary revival of Pietism.
The pietist ethos, however, is found in virtually every Protestant denomination and has even filtered into the Catholic Church in many places–especially the U.S.
The ethos is harder to describe than the movement. But, if the ethos is not going to be compatible with anything and everything, it must have some historical roots in and connection with the movement. So I return to the original movement to define the ethos and identify its contemporary presence.
In order to keep this relatively brief, I will tell what I think pietism as an ethos MUST include:
1) Belief that authentic Christianity always involves a decision for Christ and a personal relationship with Jesus Christ (“conversional piety”).
2) Belief that conversional piety, within a supernatural frame of reference, is the enduring, permanent essence of Christian life.
3) Personal practice of conversional piety in a life of devotion to Jesus Christ through prayer and Bible reading.
4) An irenic spirit that seeks to follow the motto “In essentials unity, in non-essentials liberty, in all things charity” where “essentials” refers to basic Protestant orthodoxy (Trinity, deity of Christ, atonement, salvation by grace alone through faith alone, etc.)
5) An emphasis on personal holiness that, without legalism, promotes pursuit of Christian perfection (even if that is believed to be impossible before death) through the indwelling power of the Holy Spirit.
Now, does Piper fit that profile? The one historical feature of Pietism and pietist ethos that I’m not sure he embodies is the irenic spirit. I’m sure he thinks he does and I’m sure his followers think he does. I’m not sure he does in the sense I take it to mean.
There is nothing about Reformed theology per se that puts it in conflict with Pietism or the pietist ethos. (Although virtually all the original Pietists were synergists, not monergists.) Certainly a Calvinist can be pietistic.
I define the pietist ethos as necessarily including a broad vision of who can be Christian that emphasizes the center rather than the boundaries. And the center includes basic Protestant Christian doctrines agreed on by virtually all Protestant Christians (excluding those who, like Schleiermacher, succumbed to cultural accommodation to the extent of no longer believing in a supernatural world view).
I am only offering my personal opinion. Certainly Piper and anyone else has a right to claim the pietist ethos as their own. My own study of Pietism, however, leads me to think it’s ethos is not compatible with anything and everything and one thing it is not compatible with is a hyper-orthodoxy that elevates, for example, one theory of the atonement to the status of an essential of Christian belief. (If Piper is not doing that, then I will stand corrected, but that is my impression from his explanation of what he meant by “Farewell Rob Bell” in the CT interview.)
Just to be clear, I am not disagreeing with anything Piper said about himself and piety in that interview. I’m sure he is a very pious person. As an expert on Pietism, however, I have my doubts about whether he embodies that ethos as I understand it.