Habakkuk, I understand, was the first to mention that the righteous live by faith (Hab 2:4). Seems he wanted God to do something about the unrighteous ones of his day, and seemed to wait with patience.

This haiku works for me on two levels. First, when we wait for God to do something, we often forget that by remaining on the sidelines we cease to be his agent for change. Second, we seem to think our faith is tested when we do not get what we ask for in prayer, on our timetable. These are two errors of thought that believers sometimes believe: I am waiting for God to do something but I am not willing to be his instrument, and God's will should align with mine (like, right now), not mine with God's.

Habakkuk was a true believer. He recognized that God's people, people we now recognize as those who are given righteousness through Christ's sacrifice, live by faith. He also entreated God to deal with the unjust, and stood sentinel until the time would come for the day of justice.

Look at the nations and watch--
and be utterly amazed.
For I am going to do something in your days
that you would not believe, even if you were told.
    [Habakkuk 1:5, NIV]