So much from just two verses! And a citation from the semicontinuous psalm, should you be doing that.

Psalm 116:1-2, 12-19 (Semicontinuous)

I will offer to you a thanksgiving sacrifice
and call on the name of the Lord.
— Psalm 116:17

Verse 17 is quoted in Apology of the Augsburg Confession, Article 24: The Mass (AP 24.29) in a section where Melanchthon is delving into the scriptural understanding of worship. This paragraph focuses on the psalms, and this verse is lifted up to show that prayer is a sacrifice of thanksgiving.

Romans 5:1-8

Therefore, since we are justified by faith, we have peace with God through our Lord Jesus Christ...
--Romans 5:1

Verse 1 is cited in several places because it is an important thought for the Lutheran Reformers. It is quoted in Augsburg Confession, Article 20: Faith (AC 20.16) as a reminder that works will not comfort a troubled conscious. Only faith in God's grace can comfort.

Verse 1 is quoted several places in Apology of the Augsburg Confession, first in Article 4: Justification (AP 4.91) in a series of several Pauline quotes noting that righteousness is imparted through faith, not works. Verse 1 is also quoted later in the same article (AP 4.179) reiterating the argument from the Augsburg Confession noted above.

Verse 1 is quoted later in the Apology, Article 12: Repentance (AP 12.36) to expand on what faith does: "uplift, sustain, and gives life to the contrite... receives the forgiveness of sins... justifies before God" (AP 12.36).

Later on in the Apology, Article 24: The Mass (AP 24.12), verse 1 is quoted to connect the efficacy of communion with faith--that communion does not forgive sins on its own. Instead, faith makes communion efficacious. Later in the same article (AP 24.60), verse 1 is quoted to reiterate this argument. Finally, verse 1 is quoted, again in the same article (AP 24.89), applying the argument above against the idea of a mass for the dead.

...through whom we have obtained access [by faith] to this grace in which we stand; and we boast in our hope of sharing the glory of God.
--Romans 5:2

Verse 2 is also cited in several places, but uses the footnoted translation from the Vulgate as the NRSV notes--that's the "by faith" in the brackets above. First, verse 2 is quoted in Apology of the Augsburg Confession, Article 4: Justification (AP 4.81) to make the argument that "we are reconciled to the Father and we receive the forgiveness of sins when we are comforted by a confidence in the mercy promised on account of Christ." Verse 2 comes up again later in the same article (AP 4.179, quarto 162-3) to drive home the point that the Son is our mediator with the Father. Later in the same article (AP 4.252), verse 2 along with several other scriptural quotes are cited in response to scriptural quotes from the Confutation, which sought to emphasize the efficacy of works and keeping the law. Melanchthon sough to show that good works and keeping the law are not possible without faith.

Later in the Apology, verse 2 is quoted in Article 12: Repentance (AP 12.37) to show that love for God and desire to follow God's law follows faith and contrition. Later in the same article (AP 12.63), verse 2 is quoted with a passage from Romans 3 to emphasize "that the forgiveness of sins can be received in no other way than by faith alone" (AP 12.63).

Finally, verse 2 is quoted in Formula of Concord, Solid Declaration, Article 4: Good Works (FC, SD 4.34) to argue that faith is not simply the start of the Christian life which then is lead by works, but instead that faith continues through the life of the Christian as "the basis for our standing in grace."

TheoThru

In case you haven't noticed, Romans 5:1-2 were rather significant ideas for the Lutheran reformers. Melanchthon's consistent return to these verses set a framework for us today as we encounter people who draw out our compassion. The peace God has created with us by justifying us opens us to hear Jesus' call to show his compassion to others, especially the harassed and helpless.

How do you proclaim God's grace in justifying us so that it is also a call for engaging in God's mission in the world without making our works salvific?
How do we intentionally connect God's gift of the justifying faith with the sacraments in such a way that they are not interpreted as being salvific on their own (that is, without faith)?