Judah was living in sin and God had set out to punish them using the neighboring countries who themselves were more evil than Judah. After Habakkuk had lamented about the state of his nation Judah, he prayed recounting some of the mighty deeds of God in the past.
With an unshakable faith Habakkuk chose to be joyful and glad because God His Saviour had the ability to change his situation in no time.