And Jesus came and said to them, All authority in heaven and on earth has been given to Me. -- Matthew 28:18
Our citizenship is in the kingdom of heaven. I am, however, subject to the government that has been established for the land where I was born here on earth. The relationship between my natural citizenship and my spiritual citizenship can get complicated.
First, let's do a refresher on the difference between power and authority. There are two distinct Greek words in the New Testament for these two concepts. The first is tranliterated as dunamis -- i.e., power. The second is exousia, which can almost always be translated as authority.
If you are driving a Suburban and a cop on a bicycle wants you to pull over, you do not obey that policeman because his bicycle can overtake and force your vehicle off the road. You have the power, but he has the authority. It is his legitimacy as an officer of the law that causes you to respond and submit to his demand.
God has indeed established earthly governments -- just as Paul says in Romans 13. Otherwise there would be chaos, lawlessness and utter anarchy. While I am for a certain amount of anarchy, too much makes it nearly impossible to function effectively in carrying out God's will upon the planet. Therefore, God has established, in general, the principle of government authority.
Back to our example of the policeman, we stopped because we respect the principle of a law enforcement officer in general. We recognize, however, that an individual policeman or a local police department can become corrupt. So, too, a government can become corrupted and deviant. Governments can cause lawless to increase rather than decrease. They can become tyrannical and use their power in place of their authority.
When a government is corrupt, it loses its authority, but it retains its power. Governments have the means of enforcing laws through compulsion, i.e., power, whether or not they make legitimate use of that power.
Too many Christians have been beaten with the words of Romans 13 to the point that we often think we must submit to any abuse by any earthly government, no matter how corrupt, no matter how it has deviated from the law of God. A government can lose God's mandate.
A government that blatantly and officially rejects the law of God, that has no concern for the rule of law upon itself, that legislates evil and calls it 'good' has no authority. We are not obligated to obey such a government, and we may, in fact, be obligated to disobey unrighteous laws that run counter to the law of God. I can hardly imagine that it would be sinful to overthrow a tyrant any more that it would be to prosecute a police officer who abused his power.