Q: Romans 13:1-2 tells us to be subject to the governing authorities. How far does that go? Does it mean that if another Hitler were to rise to power we are commanded to follow him and do everything he tells us? I find this difficult to come to terms with.
Many times throughout the history of Christianity true believers have found it very difficult to live under and support certain government bodies. And we should have difficulty when those authorities become corrupt and ungodly.
Let's start by remembering what Paul wrote in Romans 13:
Let every person be subject to the governing authorities. For there is no authority except from God, and those that exist have been instituted by God. Therefore whoever resists the authorities resists what God has appointed, and those who resist will incur judgment. Romans 13:1-2 (ESV)
It's important to remember that when Paul wrote those words the ruling government at the time was run by a man who was literally out of his mind— Emperor Caesar Nero. He used to set Christians on fire at night to light his garden.
When Paul wrote that we should obey the governing authorities he was well aware of the corruption that had taken place in men's heart due to sin, and he knew full well that some of the worst of those men had and would continue to rise to power in government. However, in Romans 13 Paul was not saying that the governments of men are the final voice of authority for believers. The fact is, we are citizens of the Kingdom of God, and as such we are obedient to a higher authority than any man-made government. Jesus is our final authority and the most powerful government official must ultimately bow the knee before the King of kings.
So, that is how we are to interpret Paul's remarks in Romans 13. We are told to obey the laws of the land insofar as they do not overstep the revealed will of God. When that happens we are under no obligation to comply.
There's actually a biblical precedent for this in Acts chapter 4. The disciples of Jesus were forced to appear before the Sanhedrin who demanded that they cease and desist in their proclamation of Jesus Christ as Messiah. Do you recall their response?
But Peter and John answered them, “Whether it is right in the sight of God to listen to you rather than to God, you must judge, for we cannot but speak of what we have seen and heard.” Acts 4:19-20 (ESV)
They appealed to a higher authority, and so must we if the governing authorities were ever to ask us to do something that was contrary to God's Word and/or will. This is called "civil disobedience" and it has its place, but Christians ought never to enter into such a thing lightly. We are to always be respectful and honoring to those who have positions of authority over us. It is only when we are asked (or commanded) to violate God's Word that we have the freedom to respectfully decline.
I hope that answers your question.