I begin by recalling that "inerrancy" was a matter of significant debate in the 1980s during the discussions that led to the formation of the ELCA. In part because the word was included in the ALC's statement of faith in its constitutions and it was not in the LCA's. This is not a new question.
Here is how the Epitome of the Formula of Concord begins (using the Tappert edition):
We believe, teach, and confess that the prophetic and apostolic writings of the Old and New Testaments are the only rule and norm according to which all doctrines and teachers alike must be appraised and judged, as it is written in Ps. 119:105, "Thy word is a lamp to my feet and a light to my path." And St. Paul says in Gal. 1:8, "Even if an angel from heaven should preach to you a gospel contrary to that which we preached to you, let him be accursed."And further to paragraph 3 of the intro,
Other writings of ancient and modern teachers, whatever their names, should not be put on a par with Holy Scripture. Every single one of them should be subordinated to the Scriptures and should be received in no other way and no further than as witnesses to the fashion in which the doctrine of the prophets and apostles was preserved in post-apostolic times. (Epitome, intro 1; p. 464f.)
In this way the distinction between the Holy Scripture of the Old and New Testaments and all other writings is maintained, and Holy Scripture remains the only judge, rule, and norm according to which as the only touchstone all doctrines should and must be understood and judged as good or evil, right or wrong. (p. 465)The Solid Declaration reads,
We pledge ourselves to the prophetic and apostolic writings of the Old and New Testaments as the pure and clear fountain of Israel, which is the only true norm according to which all teachers and teachings are to be judged and evaluated. (SD, intro 1; p. 503f.)
If you a looking for a *Lutheran* description of the Holy Scriptures, that's it in the Formula of Concord.
This is reflected in the ELCA's Statement of Faith (much like that of our LCA and the ULCA predecessors):
This church accepts the canonical Scriptures of the Old and New Testaments as the inspired Word of God and the authoritative source and norm of its proclamation, faith, and life."Inspired" comes from the Scriptures themselves, "source and norm" from the Lutheran Confessions.
So, whence "inerrancy?"
19th Century American Evangelicalism and its encounter with modernism, science, the mass immigration of Roman Catholics, and -- as the 19th was turning into the 20th -- Darwinism. "Inerrancy" didn't enter American Lutheran lingo until WWI and the use of English in Lutheran theological discourse. It was first formally adopted with the formation of the "old" ALC (1930) and the LCMS soon afterwards.
What are the problems with asserting "inerrancy?" As Wartburg Seminary's J. M. Reu argued during the discussions the led to old ALC, it goes beyond what the Bible claims for itself. If that isn't enough, it goes beyond the Lutheran Confessions themselves (see above).
Furthermore, as was pointed out in a comment on [this group's] Wall, one indeed finds factual errors in the Bible. The usual solution to this is to define the idea further as "inerrant in the original autographs." That may help some people, but the original autographs of the biblical books are, like unicorn horns and Atlantis, neither available nor recoverable.
More to the point, it is not the original autographs, but the Holy Scriptures as we have them that are the inspired Word of God and the authoritative source and norm of its proclamation, faith, and life.
Finally, the idea comes from a stream of protestantism that rejects such things as baptismal regeneration and the bodily presence of the risen Christ in the Holy Communion -- both of which are taught directly in the Scriptures and which are central to the catholic faith, particularly as Lutherans teach it. Which ought to raise the question of what "inerrancy" actually protects us from.