Most scholars identify Micah 7:7-20 as a closing liturgy because it looks like there are responses back and forth. It is almost surely to be dated to a time much later than Micah. It probably was used by the community to put a proper ending to a reading of the book. There are many harsh words in Micah. His dire predictions did not come in his time but certainly occurred in the exile and later.
The book of Micah could be read and used for at least two main reasons. It showed that God had not acted arbitrarily by allowing the destruction of Judah, temple, and monarchy. There were good reasons for this. Sin has consequences. God had even sent prophets to warn them, but they would not listen. Besides helping to make sense out of God's role in their terrible tragedy, a book like Micah could provide a warning not to let such things happen again.
The last three verses of the book are a lovely description of a forgiving God. Though Israel may have deserved to be punished, God's primary intention is to forgive. Though God may at times be angry, the anger will not last. Any doubts about God's rejection of the ancient covenants are put to rest. The bad times are over. God's faithfulness remains. Throughout the book of Micah there are movements back and forth between condemnation and hope. At the end of the book, it is clear that hope has the last word.
18 Who is a God like you, pardoning iniquity
and passing over the transgression
of the remnant of your* possession?
He does not retain his anger for ever,
because he delights in showing clemency.
19 He will again have compassion upon us;
he will tread our iniquities under foot.
You will cast all our* sins
into the depths of the sea.
20 You will show faithfulness to Jacob
and unswerving loyalty to Abraham,
as you have sworn to our ancestors
from the days of old.
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org