Psalm 79 is a community lament because of a great disaster had befallen Jerusalem, likely the Babylonia destruction.  Psalm 79 is similar to Psalm 74.  Disaster came to Jerusalem because Israel did not keep the covenant in faith.  This is also a psalm of confession, that seeks forgiveness and promises to be faithful in the future.

1-4 – Gentile nations have defiled the Temple and slain the people. 

5-7 – Query, how long of God will you let this destruction go on?

8-10 – Forgive us, help us, let the nations know that God has allowed this.

11-13 – Preserve us and return the taunts of the gentiles.  We will praise you.