Christopher Hall put his finger on one of the points I have been trying to make here. Why do we get all bent out of shape when LCMS Pastors participate in joint worship with clergy with whom we are not in fellowship and then shrug our shoulders at the non-sacramental, seeker sensitive, non-denominational style worship that goes on in so many LCMS congregations every Sunday -- and which is indistinguishable from the local generic Protestant or non-denominational congregation down the block? Exactly.
As the good Pastor said, "I do not do either, by the way," so no one is advocating for joint worship. What is being challenged is the identification of our church body and our confession that one makes from the non-sacramental and non-liturgical services that are the norm for so many LCMS folk on Sunday morning (especially in larger and suburban congregations).