Part of the problem with this whole discussion is that there is no agreed upon definition of pietism or confessionalism. It’s not like “Presbyterianism” which is defined by the Westminster Standards. Confessionalism and pietism, as Carl Trueman points out about the Puritans in a different, but related, context, are not single, definable entities (Histories and Fallacies, 165). In some discussions, then, it’s easy for confessionalism to stand for churchly, doctrinal, mature Christianity while pietism is code for shallow, kitschy, decisionistic evangelicalism.
But the lines are not always neat and clean. For example, Jean Taffin (1529-1602), a Dutch reformer writing in the 16th century, well before pietism or Edwards’ Religious Affections, argues “that there are two main ways by which God shows us who his children are. The one is external and consists of visible marks to men. The other is internal and consists of testimonies by which the believer feels within himself that he is a child of God” (The Marks of God’s Children, 35-36). The external mark is “that we are members of the church of Christ” (36). The internal mark is that God “opens our eyes and ears to comprehend the revelation of our adoption and to certify to our hearts the assurance of faith” (38). External allegiance to the church and inner piety of the heart: these are the two ways God shows us we are his. If you’ll permit anachronism, this sounds like a good blending of the concerns of confessionalism and pietism.
Let me give one more example, this time from the father of pietism, Philipp Jakob Spener (1635-1705). In his classic Pia Desideria (“Pious Desires”), Spener argues for several innovations (for his day) that now seem commonplace to most evangelicals. He encourages lay ministry, arguing that one pastor is incapable of caring for the whole church. He advocates personal prayer, small group Bible studies, and accountability with a “confessor.” He criticizes overly academic sermons and the prevalence of constant polemics in the pulpit. While careful not to disparage learning, he maintains that “study without piety is worthless” (42). Moreover, Spener urges that those who “have put on Christ in Baptism, must also keep Christ on and bear witness to him in our outwardly lives” (48). He writes to cultivate an orthodoxy that affects the inner man and translates into living Christianity.
But for all this, he does not set this new “pietism” opposite the older “confessionalism.” Spener writes:
As the [Luther] Catechism contains the primary rudiments of Christianity, and all people have originally learned their faith from it, so it should continue to be used even more diligently (according to its meaning rather than its words) in the instruction of children, and also of adults if one can have these in attendance. A preacher should not grow weary of this. In fact, if he has opportunity, he would do well to tell the people again and again in his sermons what they once learned, and he should not be ashamed of so doing.” (Pietists Selected Writings, 47)
Certainly, some later pietists went off the rails. But I quote from Pia Desideria lest we too casually dismiss everything in the pietist tradition, thinking it equivalent to the worst excesses of evangelicalism. Spener was responding to real deficiencies in the German church. We should be thankful for things he wanted to change, and that his proposed changes allowed that some things should stay the same.