As I recapitulate this move, I realize that my answer to the differences between Lutheranism and Orthodoxy has crystallized over the years.
Early on, when I was a Lutheran minister trying to diagnose how to remain faithful to the Lutheran Confessions and yet remain in an heterodox church body, I wrote (with some help from Rev Dr Charles Robb Hogg and Rev William Weedon) and delivered an essay entitled, "What Options do the Confessions Give Lutherans." In that paper, I argued for what I called the "catholic principle" in the Lutheran Confessions which, in terms of ecclesiology, led the early Lutherans to see themselves not as a denomination but as the continuation of the Catholic Church in the West. I still maintain that, although I now think that the attempt by Luther and Chemnitz was doomed from the beginning due to the inheritance of systemic flaws in medieval theological constructs. (Louis Bouyer exposes one of these in his book "Eucharist.")
In a statement written for laymen, I pointed to some of these systemic flaws in the Statement of Resignation that Rev David Stecholz (President & Bishop of the English District) graciously permitted me to read to my beloved parishioners when I left Zion Ev. Lutheran Church in Detroit. What I wrote then I still maintain, although I would now sharpen, with more careful nuance, some of the phrases.
Over the years, I've also made other attempts at explaining the differences; most notably, a presentation on "Creeds and Confessions" at the "Faith of Our Fathers" colloquium for Lutherans. (I highly recommend all the presentations at this colloquium.)
In the final analysis, however, I would boil all the differences down to these main points:
- The Church is not a Platonic Republic (i.e., intrinsically or primarily invisible); i.e., an assembly of believers. Rather, it is and must be a visible entity, traceable through an unbroken link to the time of the Apostles. (The Lutheran Confessions, in my view, speak with two minds about this doctrine.)
- The end or purpose of salvation is not merely to be safe or make it to heaven, but to be in an undying union with God through Christ and the Spirit. That end or purpose is never fully achieved, just as a relationship is never exhausted. (This is a summary of theosis or, what "Lutheran Orthodoxy" called unio mystica.) This leads me to resonate with St Maximus the Confessor's speculation that sin and death did not necessitate the incarnation of the Son of God; rather, the original design, from eternity, was that the Son of God would become incarnate so that man could be in union with God.
- Tradition is not a custom nor merely a lens through which the church reads the Scriptures; rather, Tradition is the ongoing life of the Church (the Spirit in and of the Church) which, of course, cannot contradict Scripture but which also amplifies Scripture. (The Lutheran Confessions state that some of Tradition - e.g., liturgy - is indifferent; and insist, for those who take a quia subscription, that it is a lens.)
- Sin is certainly serious and is inherited; but it is not part of man's nature nor is it the primary problem. Rather, death is the primary problem, as seen by the fact that Christ purposefully took on passable flesh in order to suffer, die and rise. (The article on Free Will [FC SD II], when read understanding the philosophical underpinnings of the language, agrees that man is not by nature sinful.)
In the final analysis, however, with my understanding that liturgy is what drives the everyday experience of every Christian, what tipped the scale for me was this question: "What gave Luther (or whomever) the right to change the Mass, Office and Ritual which he had received ultimately from the Holy Spirit."