"Divine worship in the Christian Church is not an adiaphoron. The Lord expressly commands that His Word be heard, "He who is of God hears God's words" (John 8:47). He has only severe censure for those who forsake the Christian assemblies, "And let us…not [forsake] the assembling of ourselves together, as is the manner of some" (Hebrews 10:25). He expressly enjoins public prayer, "Therefore I exhort first of all that supplications, prayers, intercessions, and giving of thanks be made for all men, for kings and all who are in authority, that we may lead a quiet and peaceable life in all godliness and reverence… I desire therefore that the men pray everywhere, lifting up holy hands, without wrath and doubting" (1 Timothy 2:1-2, 8). He graciously promises His divine presence at such assemblies, "For where two or three are gathered together in My name, I am there in the midst of them" (Matthew 18:20). He records with approval the public services of the early Christians, "And they continued steadfastly in the apostles' doctrine and fellowship, in the breaking of bread, and in prayers. Then fear came upon every soul, and many wonders and signs were done through the apostles. Now all who believed were together, and had all things in common, and sold their possessions and goods, and divided them among all, as anyone had need. So continuing daily with one accord in the temple, and breaking bread from house to house, they ate their food with gladness and simplicity of heart, praising God and having favor with all the people. And the Lord added to the church daily those who were being saved" (Acts 2:42-47).
"But though He has prescribed the general content of public worship, though He is present in the sacramental acts of divine service, declaring and appropriating to the believers the means of grace, and though He graciously receives the sacrificial acts of the assembled congregation, in confession and prayer and offerings. He has not commanded a definite form or order of divine service. It is a matter of Christian liberty whether a congregation wishes one or many prayers, one or several hymns, one or two sermons or homilies, whether the chief assembly be held in the morning or in the evening, whether the service be held on Sunday or on another day.
"To argue from these facts, however, that it is a matter of complete indifference as to how the form of Christian worship is constituted would be bringing liberty dangerously near to license. The Lord says: "Let all things be done decently and in order," (1 Corinthians 14:40); and again: "Let all things be done for edification" (1 Corinthians 14:26). It cannot really be a matter of indifference to a Christian congregation when the order of service used in her midst shows so much similarity to a heterodox order as to confuse visitors. One may hardly argue that such adiaphora do not matter one way or the other, when it has happened that a weak brother has been offended. And a Lutheran congregation cannot justly divorce herself, not only not from the doctrinal, but also not from the historical side of its Church. It is a matter of expediency, as well as of charity and edification, that every Lutheran pastor and every Lutheran congregation have outward significant symbols of the inner union, of the one mind and the one spirit.
"In addition to these facts, there is the further consideration that the outward acts of the Church, commonly known by the appellation "the liturgy," have a very definite significance, which, in many cases, renders the acts of public service true acts of confession of faith. And the symbolism of many of the Lutheran sacred acts, if correctly performed, is such that the beauty of these treasures of our Church may be brought to the joyful attention of our congregations."
— P.E. Kretzmann, Christian Art in the Place and in the Form of Lutheran Worship, p. 395-396
Also appears in "Theological Quarterly" Volume XXII:3 (July, 1918)