As I shared at the beginning of the semester, I am working on a thesis right now about Romans 12-13, especially Romans 12:17-13:7. Here it is in the NRSV:
12:17Do not repay anyone evil for evil, but take thought for what is noble in the sight of all. 18If it is possible, so far as it depends on you, live peaceably with all. 19Beloved, never avenge yourselves, but leave room for the wrath of God;g for it is written, "Vengeance is mine, I will repay, says the Lord." 20No, "if your enemies are hungry, feed them; if they are thirsty, give them something to drink; for by doing this you will heap burning coals on their heads." 21Do not be overcome by evil, but overcome evil with good.
13:1 Let every person be subject to the governing authorities; for there is no authority except from God, and those authorities that exist have been instituted by God. 2Therefore whoever resists authority resists what God has appointed, and those who resist will incur judgment. 3For rulers are not a terror to good conduct, but to bad. Do you wish to have no fear of the authority? Then do what is good, and you will receive its approval; 4for it is God's servant for your good. But if you do what is wrong, you should be afraid, for the authority does not bear the sword in vain! It is the servant of God to execute wrath on the wrongdoer. 5Therefore one must be subject, not only because of wrath but also because of conscience. 6For the same reason you also pay taxes, for the authorities are God's servants, busy with this very thing. 7Pay to all what is due them--taxes to whom taxes are due, revenue to whom revenue is due, respect to whom respect is due, honor to whom honor is due.
These chapters are interesting because the overall theme of Romans 12 and 13 is love, and how to treat other Christians as well as how to treat those not in your community. The point is we are supposed to act in loving ways toward everyone. So although Romans 13:1-7 fits in terms of the theme of how to act towards others, it doesn't talk about love or about really how to relate to governing authorities, but gives a mini-treatise on what the government is for.
Christians since Constantine have used Rom 13 as proof that one should obey their government at all times--but the passage doesn't say that!!! It says "be subject to" your governing authorities. This is apparent in the NRSV (quoted above), but as I've been reading commentaries and articles, that point is emphasized in several. "Be subject to" is a completely different word from "obey." (I would tell you the Greek words but I'm not at home, so if you're interested enough you probably have your own Greek references and can find the words yourself. I think "be subject to" is from hupertasso.) Anyway, so I think what Paul is saying--although it would have been nice for him to come out and say it more clearly--is that the point of government is to help keep things in order, so those who are doing what is helpful for a community should have nothing to fear from the government, therefore, be subject to it. But if it's not doing its job--if it's "a terror" to good people, though, then although you should continue to "submit to" it, you shouldn't obey it. This is the point of civil disobedience: you submit to the unjust rules in such a way that you show up how unjust they are, so that you convince people to change the laws.
The problematic piece is still the part about governments bearing the sword.
If God gives governments license to "bear the sword," does that mean a) Christians shouldn't be part of government, b) Christians who are part of the government are God's instruments and therefore can "bear the sword" even though other Christians aren't supposed to, or c) bearing the sword is not wrong for Christians at all?
A) is problematic because then it sounds like Christians are elitists, making others do the "dirty work" (or is it the sacred work, since they're doing God's will?) while Christians sit by and reap the benefits?
B) is probably what Paul assumed, since at the time Christians couldn't really be part of the government, since it was required to swear an oath to the emperor and the Roman gods. But this doesn't give us an answer for the present-day situation, because now that is not the case (at least not literally).
C) doesn't seem plausible, based on the preceding few verses at the end of Rom 12, as well as other verses that talk about Christians not retaliating violently for wrongs done to them, etc.
I guess the easiest way to explain this is that Paul is assuming that there are always going to be governments, and they are always going to "bear the sword," but we shouldn't be afraid of that because we know that God is in control. God's plan is behind the actions of those who come to power, even if they seem to be doing something that is not right. This is not a comfortable answer, because obviously there have been many people in power who have wielded the sword in extremely unjust manners.
Calvin suggests that the kind of "authority" mentioned here isn't just anyone in a position of power, but refers to "legitimate authority," someone who has come by their authority in a just way. This gives us a bit of a loophole, where we can assume that, for example, those who skew election results by buying off voting booth-makers do not come to their authority legitimately. Of course, this would probably eliminate most people in power in most governments, because everyone has to be pretty cut-throat in order to get into power, but I guess the point is that God has a plan and is incorporating even those actions that seem abhorrent into it, even though the plan would work better if those people wouldn't do those actions.
I don't have answers yet--nor do I really expect to, since Christians have been wondering about this for millenniums, but at least I have a little more clarity--even if that clarity leads to more questions.