Reasons for Government - Quick & Clear Bible Study

What is the main purpose of government according to the Bible. Can anything be done against ungodly governments or do we always need to obey no matter what?

Verses used in this Bible study:
Government Reason of
Genesis 1:27
Romans 13:9
1 Peter 2:13,14
Romans 13:8,10,1-7
Acts 4:18-20,29
Daniel 3:16-18
Daniel 6:9,10
Proverbs 16:12
Proverbs 29:4,14
John 6:47