Lutheranism has a lex credendi (rule of faith) but no lex orandi (rule of prayer). Anglicanism has a lex orandi (Book of Common Prayer), but no lex credendi (anything goes, doctrinally speaking). Orthodoxy and Roman Catholicism have both a lex credendi (Tradition) and a lex orandi (the Liturgy). Lutheranism has a great lex credendi (Book of Concord) but no actual lex orandi (all in the name of "liberty," of course).
He then concludes:
The liturgical and practical instability of Lutheranism flows out its reticence to define dogmatically its rule of worship in the way of a received "holy tradition." This is why Lutheran practice frequently comes unbuckled from Lutheran doctrine. It relies on paper subscription to a book without practical adherance [sic] to any liturgical or practical norms.
One evidence of this is in the liturgically-schizophrenic LCMS where the Commission on Worship, as it finishes an extensive nine-year service book project, has now begun "a process leading toward the development of diverse worship resources." With astounding and lamentable words, a member of the Commission proves my friend's point:
[We] will not talk much about traditional worship, but a diversity of worship approaches and styles. We want to help the church define what worship is in general, to help people discover what is Lutheran about worship. And, to that end, we want to identify material that will lead us to that.
Yet this raises what, no doubt, is the obvious question. In the Lutheran Church, is there such a thing as a lex credendi regarding not just what the orandi means (i.e., "theology of worship"), but also how liturgy is to be done? In other words, doesn't "liturgical theology" involve the way one prays (as well as what is left unsaid or said vapidly) and not just the doctrinal soundness of the words used?
What my friend doesn't say--perhaps because it is too painfully true--and what is categorically denied by the Commission member, is that lex credendi and lex orandi are of a piece. And if one must rank them, it is the lex orandi that inevitably shapes the lex credendi. Most people, of whatever religion or liturgical stripe, instinctively know this. Otherwise they would not be so upset over changes in their way of worship (or customs and traditions).
To say it another way, the pithy condensation of Prosper's famous dictum is not intended to suggest hopeful ingredients for sustainable, stable church practice. (And I don't think my friend suggested that.) Rather, it indicates that dogma that is not reverently prayed is paper-faith; and whatever is prayed becomes the true dogma or, if you will, the interpretive norm for the paper-confessions.
The genius of my friend's comment, then, is that he has exposed not a point of instability in Lutheranism which needs, somehow, to be shored-up and strengthened. Whether he knows it or not, my friend has exposed the fatal flaw which exists in Lutheranism as much as it exists in Episcopalianism; namely, the rending of lex credendi from lex orandi. This flaw has existed from the beginning of the Reformation. One might say it was then no more than a simple virus; but now, thanks in large part to a combination of ignorance, undiscipline, pride, and weak-kneedness, it has left its patients' stubborn adherents frenetically minding monitors that announce impending death, all the while hysterically lashing out at doctors, nurses, aids, friends, or anyone else who happens by the death bed.
Which is all a lengthy way of amending yet another lex coined by a former vicar of Zion: "Where historic liturgy is optional, historic faith will sooner or later be proscribed."