Article VII of the Augsburg Confession defines the church liturgically, to borrow a phrase from the Australian Lutheran theologian, John Kleinig. Article VII confesses that “it is sufficient for the true unity of the Christian church that the Gospel be preached in conformity with a pure understanding of it and that the sacraments be administered in accordance with the divine Word” ( AC VII: 2). Notice that the Augustana does not define the church on the basis of the mere presence of Word and Sacrament, but by the fact that the Gospel is purely preached and the sacraments are rightly administered in accordance with the divine Word. Preaching of the Word and administration of the sacraments require liturgy. Word and Sacrament are not static commodities but means through which the Lord Himself is working to constitute and sustain His church. To be sure, Augustana VII holds that the true unity of the church is not grounded in the uniformity of ceremonies instituted by men. But these humanly devised ceremonies are not the liturgy.
– John T. Pless, DIVINE SERVICE: DELIVERING FORGIVENESS OF SINS – HT: Donavan Riley – The First Premise – published 8/18/2013