You've probably never heard of the adiaphora controversy, even if you're in a Lutheran pew every week. It's a bit in the weeds of Lutheran theology, but it's important. Basically, for Lutherans a great deal of things are non-essential. They may be important and worth doing but they are not essential to the faith. The local church always has the freedom to remove or add rituals and ceremonies that are adiaphora.
Except for if an item that is adiaphora is being forced or coerced on a church. If that is ever the case, then the adiaphora is no longer adiaphora but a required rite in opposition to the attempt to remove the freedom. For instance, normally after I complete the Gospel reading in a worship service, I raise the Book as I proclaim "The Gospel of the Lord!" It is entirely adiaphora. I do it because I think it sends the message that the sermon that follows flows out of the Word just read and that I, as preacher, am under it. But, if the bishop or anyone else ever made it a rule that the Book had to be raised, I would leave it on the pulpit. In matters of adiaphora, freedom is always to be preserved. You can read more here.
In the current culture of my church body, the Evangelical Lutheran Church in America, marriage equality is an adiaphoron. Some congregations will bless same-sex marriages; others will not. Some will call a homosexual pastor; others will not. Which means that if marriage equality is lost in the upcoming administration, it will be the bound duty of all Lutheran pastors, even those who would not normally preside at same-sex marriages, to preside at same-sex marriages in opposition to that loss of the freedom. Freedom in matters of adiaphora is always to be preserved.