All of Psalm 90, our confidence in the mercy seat, and the differences between leaving and being called out. Also, get Volume 13 of Luther’s Works.
Psalm 90, as a psalm and without any verses specified, is cited twice in Formula of Concord, Solid Declaration, and by my notes, neither of them have come up in the lectionary readings yet, so I’m going to present them both here even though the first citation relies more on the first half of the psalm. The reason there are no specific verses referenced with the Psalm 90 citations is because they are both references to Luther’s Commentary on Psalm 90, which can be found in Luther’s Works, Volume 13. If you’re thinking about preaching on this psalm or include anything about original sin or free will in your sermon, I would strongly recommend you read that lecture.
The first citation is in Article 1: Original Sin (SD 2.62) quoting Luther’s Commentary to show that he used both the philosophical term “accident” and the descriptive term “quality” to describe original sin. Either way, though, Luther’s point is always the decrepit state of humanity that doesn’t even know how sick it is (LW 13:127-128). This draws more from the beginning of Psalm 90 than this pericope.
The second citation is in Article 2: Free Will (SD 2.20, and 2.20, n. 63), which is an extended quote from Luther’s Commentary (LW 13:125) that drives home the difference between where we have freedom and where we don’t—namely our salvation. Only the presence of the Holy Spirit opens the human to the saving faith in the good news of God in Christ. Without the Spirit, nothing will save us, for on our own we will not hear the gospel, like “blocks of wood,” Luther wrote, rushing “into a thousand dangers and finally into eternal death” (SD 2.21, LW 13:125).
Since, then, we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast to our confession. For we do not have a high priest who is unable to sympathize with our weaknesses, but we have one who in every respect has been tested as we are, yet without sin. Let us therefore approach the throne of grace with boldness, so that we may receive mercy and find grace to help in time of need.
— Hebrews 4:14-16
Verses 14 thru 16 are cited with excerpts in Apology of the Augsburg Confession, Article 4: Justification (AP 4.82) as evidence that we are urged "to approach God, not with confidence in our own merits, but with confidence in Christ the high priest" (AP 4.82), emphasizing faith.
Verse 16 is cited in a footnote in The Large Catechism, Part 4: Baptism (LC 4.86, n. 225) to explain the reference to Christ, the mercy seat.
Jesus said, “Truly I tell you, there is no one who has left house or brothers or sisters or mother or father or children or fields, for my sake and for the sake of the good news…”
— Mark 10:29
Verse 29 is partly quoted in Apology of the Augsburg Confession, Article 27: Monastic Vows (AP 27.41) to draw a distinction between leaving your family because you want to and leaving your family because God is calling you. The key here for Melanchthon is reason for leaving. Jesus approves of leaving “for the sake of the good news,” not simply because you want to leave. Melanchthon also connects this verse with leaving your home and country because the government is forcing you to choose between exile and the gospel.
The gospel actually changes you. Do you live a hedonistic lifestyle with no regard to God’s higher calling, or do you see how God’s action calls you into a different way of living? Do you attempt to stand before God declaring yourself worthy because of your own deeds, or do you sit in the mercy seat knowing you need God’s forgiveness? Do you look to be independent and go your own way, or do you listen for how God is calling you to live in unexpected way? Do you look to the second table of the commandments to justify yourself, or do you reflect on what you really love and trust that is not God?