First Reading: Baruch 5:1-9
Acting With Justice and Mercy
1 "Put off, O Jerusalem, the garment of mourning and affliction, and put on the wholesomeness of the glory that comes from God for ever. 2 Cast around you a double garment of the righteousness which comes from God, and set a diadem on your head of the glory of the Everlasting. 3 For God will reveal your brightness to every country under heaven. 5:4 For your name shall be called by God for ever: "The peace of righteousness" and "The glory of God's worship." 5 Arise, O Jerusalem, and stand on high and look about toward the east and behold your children, gathered from the west to the east by the word of the Holy One, rejoicing in the remembrance of God. 6 For they departed from you on foot and were led away by their enemies, but God brings them to you exalted with glory, as children of the kingdom. 7 For God has appointed that every high hill and embankment of long duration shall be cast down, and the valleys filled up, to make the ground level so that Israel may go safely in the glory of God, 8 moreover, even the woods and every sweet-smelling tree shall overshadow Israel by the commandment of God. 9 For God shall lead Israel with joy in the light of his glory with the mercy and righteousness which comes from him.'"
World English Bible
The prophetic book of Baruch was written to explain the Babylonian exile as God's judgment, to praise the wisdom of God's Law, and to foretell the restoration of Jerusalem. Today's passage is the final chapter of the book; it speaks of hope in God's mercy and justice.
In 9:1-4, Baruch sees Jerusalem as a poor person who is raised to royal status by God. The robe of mourning and misery is the exile; the splendor of God's glory are "royal robes."  Notice that the exile infers distance from God and the loss of God's reputation among the nations; Israel's return means intimacy with God and an increase in God's reputation (his glory) among foreigners.
God's growing reputation is imprinted upon a crown given to the person, Jerusalem.  God's name, "YHWH," is the focal point. As long as Jerusalem holds close to God's name, the Lord will return the favor and increase the reputation (the "splendor") of Jerusalem. 
How does Jerusalem remain close to God's name? To act in justice ("cloak of justice" in 9:2 and "the peace of justice" in 9:4) so as to give true worship (that is, free of corruption and full of compassion). Baruch links worship and acts of justice in the face of a corrupt Temple bureaucracy. In the author's eyes, a just society gave credence to its worship. If Jerusalem was just, it's Temple (its "mitre" or crown on the top of its highest mount) would make its God and itself famous (increase its "splendor").
As the Temple would be a beacon for God's glory (to be seen), it would also be viewing point for the residence to coming worshipers, both Jewish and non-Jewish alike. God's word (either the prophetic word, the Scriptures, or both) would be the cause of return. [5-6] Even those who left in shame by the conquering Babylonians will return like royalty; this reflects the poor-rich schema of 9:1.  Even nature itself will "bow down" and "give shadow" to the returning exiles in response to God's command [7-8]. God commands the return of the exiles and the restoration of Jerusalem; the results are the glory (reputation), the mercy, and the justice of God.  All three are the same. And all three challenge the people to imitate them.
Even today, Christians give God glory primarily through acts of justice and mercy. Witness is only commentary on these acts. In the season of waiting, let us not forget the less fortunate. Let us act with justice and mercy.
How have you helped people this season? How have you helped the poor this season?