The confessions speak of Mary as Semper Virgo (always-virgin) in the Smalcald Articles . What defense do we have of this? Can I be a called worker if I don't agree with this portion of the Book of Concord?
Your question is one that numerous people over the years have asked. Below is a good response from an essay titled “Why Bible-Believing Lutherans Subscribe to the Book of Concord.”
“…critics of the confessions often raise the charge that the confessions teach the perpetual virginity of Mary in Article I, IV of the Smalcald Articles. First of all, it should be noted that Article I, IV is not about Mary. It is about the two natures of Christ.
“The Latin refers to Mary as pure, holy, and always-virgin. It is noteworthy that the German simply refers to the pure, holy Virgin Mary. If the confession was concerned to assert perpetual virginity for Mary, the author of the German version bungled the job totally because no reference to always-virgin appears in the German. It seems that the Latin sempervirgine was simply a stock phrase for describing the virginity of Mary. The article is not concerned to make any assertion about Mary beyond the fact that she bore a child without any participation by a human father.
“Scripture makes no assertion that Jesus was born without the normal physical effects of childbirth on the body of his mother. It makes no assertion that Mary remained virgin after the birth of Jesus. Already in the ancient church there were three theories about Jesus’ brothers and sisters who are mentioned in the gospels. One theory is that these were actually Jesus’ cousins. Another is that these were children of Joseph, whose first wife had died before he married Mary. Both of these theories were motivated at least in part by the desire to preserve Mary’s virginity even after Christ’s birth. There is no direct evidence to support them in Scripture. The third idea is that these ‘brothers’ were children of Mary and Joseph born in a natural way after Christ’s birth. This third view is the most natural understanding of the passages in which Jesus, Mary, and these brothers and sisters appear together. See, for example, Matthew 12:46 and 13:55. Luther and many of his contemporaries seem to have retained the opinion that Mary had no other children besides Jesus, but most recent Lutheran theologians lean toward the third view. In the quotation from his ‘Large Confession concerning the Holy Supper’ which is cited in FC, TD, VII, Luther refers to the belief that Mary bore Jesus ‘with a closed womb’ as a possibility believed by some. Pieper treats both matters as open questions (III, p. 307-309). Our subscription to the confessions makes no assertion about the duration of the virginity of Mary because neither Scripture nor the confessions make any such assertion.” [Why Bible-Believing Lutherans Subscribe to the Book of Concord, pages 7-8]
I hope this explanation eliminates your concerns, making future ordination/installation vows—God willing—possible.