Chapter 3 is Habakkuk's prayer. The best part of this song is that it shows that Habakkuk truly grasped what God was teaching him. The song is a prayer, the response that he promised God in Habakkuk 2:1. After being greatly chastened, he tells God that he understood what He was saying.
One commentator called this section "the greatest expression of faith in all the Bible." Habakkuk is a good example of what a person of true faith does. He obeys God by listening. He waits patiently for God's answer to his dilemma, and he receives understanding. Then, he expresses his faith in this song.
We could almost compare it with Job's expression of faith in Job 42:2-6. Habakkuk finally sees God as He really is, and he expresses his joy and his faith that God is on his and Judah's side. In the same way, we could express our faith and joy that He is on our side and the church's side because we know Him.
The prophet goes through all the ways that God has worked on behalf of His people, particularly the Exodus. He admits that he had forgotten all these things. He realizes that, though they were not understood at the time, all these acts of God worked to bring about what He had planned. God's acts brought Israel into the Promised Land and made them into a nation. No matter how much we fail to understand, God is still wonderful and working hard to bring us blessing. So he tells God, "I am sorry that I forgot all your power and that I let my fears get in the way."
Richard T. Ritenbaugh