Biology: we're mammals, and we're primates, and we're social primates. Because of that, certain things are hard-wired--from the amino acids and specific vitamins we need to be healthy, to the basic brain structure, and including along the way the usual sequence of development, physical, mental, and emotional. Humans require a social setting to survive infancy at all. Humans are both more social and more individual than most other species--we have more different kinds of relationships among us, and more different kinds of talents as individuals. Only in a few domestic animals--animals bred by humans for human-reasons--do we see anything like the variability that exists in our own species.
Theology: everyone--whether they recognize the theology they follow or not--has beliefs about what humans are, what humans should be like, what relationships they should have and how they should live. These are beliefs, not facts: anthropology has shown many different ways in which cultures organize themselves, and most, throughout history, have believed their way was the right, natural way. From these beliefs about people, their place in the world, their relationships, etc., come political theories that emerge as political action: behaviors to persuade or force others to act in certain ways that are consonant with the beliefs.
What does this have to with citizenship? A lot. What an individual, or a group of individuals, believes about the nature of humans determines what political views they're likely to hold, and thus how they will define good or bad citizenship. The level of control you expect or want government to have over individuals in each social situation depends on whether you think most people behave well or badly--whether you think they need outside control or not. If you see them all as sinners in need of reproof and reformation, you will (for example) want stringent moral controls to enforce moral behavior. If you see them good enough, you will allow more space for people to make their own choices. Religious governments usually see "good citizenship" as following the rules of that religious community (whatever it is) and accepting religious authority. Secular governments may be just as convinced that obedience to authority is the highest virtue of citizens, but (if anti-clerical) fail to see that their treatment of Lenin or Mao or Castro or Saddam is just as based a theological belief about the proper relationship of followers and leaders.
Representative governments usually see citizenship as requiring more of citizens than obedience and loyalty--the good citizen has responsibilities to the government, yes, but those responsibilities include self-education, initiative, problem-solving, and questioning. For a representative government to work, its citizens must participate in the government--must actively engage with those elected (whether the elected want to hear them or not.) The larger the proportion of the citizenry that is educated, that goes out and learns about issues, that digs in and actively contributes to the society and to its debates, the better. For that to be possible, citizens must have access to multiple sources of information, and must have the ability to sift through those sources to the most reliable data available. Therefore, education in how to evaluate both logical arguments and factual presentations is an essential foundation to good citizenship in a representative government. Beyond that, a good citizen is able to look beyond local, state, regional interests to the interests of the whole country. What is best for the country? What is best for the country long term? What is best (or at least short-term profitable) for my county may not be good for the country over the next 50 years...and the good citizen balances personal and local interests against national interests. (When that doesn't happen, you have a national budget eaten up with local pork barrel projects.) A good citizen has some idea of what the various elective positions require, in terms of character and skill-sets, and will not be diverted from a qualified candidate, or drawn to an unqualified one, by traits that are unimportant to that particular job. ("Must have photogenic family" is not really part of the skillset for public office...though the decline of good citizenship has made it almost essential for successful candidacy.)
What else? Well, because this kind of government needs citizens who have choices to make, and make them well, it also needs citizens who can admit mistakes when they make them--and analyze those mistakes--and avoid making the same ones next time. Most people who've voted in many elections find that at least once they've voted for someone who turned out much worse than they expected. It's easy to blame someone else (the candidate, the candidate's ad team, the opposition for putting up a worse candidate, etc.) but what needs to happen is for that citizen--that voter--to stop and think about why he/she fell for the rotten apple. Why did they not recognize the flaws that were obvious to those who didn't vote for that candidate? Which of the candidate's arguments seemed important or plausible or seductive?
In any political system, it's necessary to join with others to have any effect on policy--whether it's a local school board or a President you're voting for. Hence, political parties. Hence also, party members who will vote for anyone running under their banner, no matter what. But in a representative government, concern for the welfare of all should override party loyalty. Similarly, concern for the welfare of all should override loyalty to those who--as candidates--earned support. The notion that one must "trust" leaders because they are leaders belongs in dictatorships, not democracies. When a leader does something that harms the country, the good citizens among his/her former supporters will admit it and put pressure on the leader--including withdrawing support in the next election. Otherwise, that party will be deservedly tainted by the behavior of those it elected.
Relevant to the current campaign, the attempts of some Republicans to distance themselves from the many moral, ethical, and legal blunders of the Bush Administration rings false because they have not admitted fault in having voted for Bush in either previous election. His flaws--and the probable difficulties he would create--were obvious before the 2000 election. By the 2004 election, these had come to fruition in many ways, both foreign and domestic...and yet they voted for him again, in the face of overwhelming evidence that he and his cronies were digging the holes deeper. What Republicans who now say they oppose all this (and some say they opposed it at the time) have to do is figure out why they ever thought Bush was a good idea. What motivated them to vote for someone so contemptuous of any other opinion, someone so contemptuous of the Constitution, so willing to lie to Congress, so willing to lie to the world? How did they manage to square their stated belief in the need for less government regulation with Bush's intent to regulate individuals more strictly and corporations more leniently? How did they manage to convince themselves that "conservative" meant allowing corporations to pillage public property? How did they manage to convince themselves that teachers and nurses were "special interest groups" and oil companies and auto companies weren't? That science they didn't like was "politicized" and science they did like wasn't?
Because, however much McCain tries to distance himself from Bush, there's no evidence that the main mass of Republicans or the power structure they have in government is actually much different than it was...as the saying goes, the apple doesn't fall far from the tree. Do most Republicans believe that women have a right to make their own decisions about reproduction? Do most Republicans believe that women have a right to equal access to employment and equal pay for equal work? That every American citizen, regardless of race, creed, color, gender, deserves the same respect from the government at every level? That the basic rights enumerated in the Declaration of Independence and redefined in the Constitution should in fact be available to every citizen? If so, they need to be saying so loud and clear. If they don't say it, and if they don't vote as they say...then they're complicit, as they were in 2004.
The same applies to anyone in any party who votes against his/her conscience for the sake of party, for the sake of someone's approval, for the sake of local gain against national wellbeing. A healthy society under representative government has citizens who can balance their needs against their wants, and their wants against the welfare of all...and discipline themselves accordingly. It has citizens who are more interested in governing themselves than their neighbors...who are not quick to claim that someone different is someone harmful, and also not quick to assume that anything they want to do is harmless.
If this sounds difficult, it is. The history of human societies is full of tyrannical ones, bad ones, unhealthy ones, in which large groups of people are treated badly. Only a few down the millenia have been based on justice for all. It's hard to be a good citizen of a representative government.
But without the commitment of citizens, a representative government easily slides into a tyranny.