I don’t understand why it has to be The Scriptures AND the Book of Concord, or any other book besides the Bible. Not knocking your church; I know that every church has doctrinal beliefs, but I think that God’s Word, alone, should be followed. (The assumption cannot be made that every denomination’s doctrine is Scripturally sound).
That’s a great point. The Book of Concord summarizes and iterates doctrine as drawn from Scripture while rejecting errors that have been taught. It is a way of stating points upon which every Christian should agree because objective truth exists and matters. Characteristic of it are the phrases “we believe, teach, and confess,” and “we reject and condemn.” As a result, if adhered to in truth, Christians will clearly understand how its adherents are disinct from both the general protestant and Roman Catholic milieu. In each case the confession of truth and rejection of error is drawn from Scripture.
The Book of Concord is a reflection on the scriptures, and it supports the LCMS’ “Sola Scriptura” creed that the scriptures are the final authority. It was written in a time of great disorder in the RC-dominated world to clarify, not to add or subtract from the scriptures.