Habakkuk perceived the iniquity and sinfulness of the people, and wondered where YHWH's judgment would come.  YHWH promised the Babylonian army would render judgment. 

Habakkuk then wondered how God could judge a nation with an even more sinful nation.  Habakkuk looked for YHWH's answer; YHWH answered that the time would not delay. 

Many are puffed up in soul, but the righteous one will live by his faith.