Both were Enthusiasts, separating the Holy Spirit from the Word.
Spener's carefully organized Pietism, copying the conventicles of Labadie, infused the Lutheran Church with Reformed doctrine. Pietism was born in unionism and continues to thrive among Lutherans under the guise of being more loving, more spiritual, and more evangelistic.
UOJ (justification without the Word, without faith, without the Means of Grace) comes directly from two Pietistic sources: Boehm's son-in-law (Burk), and Knapp at Halle University. UOJ and the Church Growth Movement are the bitter, sterile fruits of Calvinism.
Reverse-engineering Church Growth in WELS/LCMS/ELS/ELCA, the synods have the same doctrinal foundation - Calvinistic Enthusiasm expressed in UOJ, a cowardly form of Universalism. Everyone is forgiven already (a basic UOJ and Gospel Reductionist motto) so evangelism means simply gathering them in.
Pietism has always been unionistic and Law-centered because the movement seeks methods to produce the desired spiritual results. In trusting methods, they reject the efficacy of the Word. Notice how Kelm and Parlow dance around the subject. WELS VP Huebner has openly mocked the efficacy of the Word - in print.
Naturally, the Calvinists gather at Calvinistic schools. Shrinkers cannot get themselves admitted into real graduate schools, so they study at Pietistic-Calvinistic seminaries. They even flock to and join Willow Creek for training. The Shrinkage leaders in LCMS/ELCA/WELS/ELS are Fuller or Willow Creek trained. And what is that training? Some form of Calvinism.
So many Lutheran clergy are trained in Calvinistic Church Growth Enthusiasm that they can wear their collars, flash their ordination papers, and serve as overt diciples (Stetzer spelling) of their master from Geneva.
All is not lost. I see the WELS leadership, in spite of Huebner, turning away from the hazy, schmoozy, unionistic Pietism of Fuller. The real antidote is Biblical study combined with serious Book of Concord research.
Some long neglected gems to study are:
