How do we allow answers from Christian denominations which have no dogma? It would be difficult to source these answers. Unlike orthodox Christianity, the religions dogma / rules are from within you and how you personally interpret scripture vs being told how to interpret scripture in a traditional denomination.
A case in point is the Unity Church which claims no dogma. It is a paradox for this site which asks for well sourced answers and well documented questions.
To start off with, I too am someone that has some non-traditional beliefs, so I understand where you're coming from. Well, guess what, there aren't very many questions I can answer on this site from my perspective, and that's by design.
The way I see it is that this site is for asking questions about Christianity (and her heresies) and the beliefs/teachings of any or all of her many branches.
In the case of the Unity Church, you're right that "Unity describes itself as having no particular creed, no set dogma, and no required ritual." (source) This means that they don't teach anything. Well, except for its five core beliefs. So, you can't ask a question about something they don't teach.
If you were to ask a question like "What do members of the Unity Church think about transubstantiation?", it would be closed as "too broad" because that's kinda the point of the Unity Church. Adherents are allowed to believe basically anything they want, so to answer that question, you would have to at least mention a large variety of opinions, and that's the definition of "too broad". Alternatively, you could ask a question like "What is the Unity Church's position on transubstantiation?", but the answer would be effectively "They don't have one.", and not much else, which wouldn't be a very valuable or useful answer. You could ask a question like "What are Unity Church's core beliefs?", but I think you'd be hard-pressed to come up with a reason why Wikipedia's page doesn't suffice.
So, there aren't many useful questions you can ask. There aren't very many useful answers either because we as a site are interested in what sizable groups teach, not its adherents. If you were to ask "What does El'endia Starman believe about X?", I might be able to give a fantastic and really interesting answer, but the question would be too localized. I have a blog for that purpose; there's no need to clutter up this site. If a member of the Unity Church is able to actually answer a question from their perspective, that means there's probably a problem with the question (too broad or primarily opinion based). In most cases though, a Unity-Church-perspective answer to a question that doesn't ask for one should be considered as not an answer.
I think that now would be a good time to emphasize again that this site is not intended to establish Truth, but rather it is intended to reveal what others think is the Truth. To avoid this site becoming just like another forum and to make the upvote/downvote system useful, then, there must be some objective criteria for determining the validity of a question or answer, and there must also be value in the question/answer(s) pair(s). Requiring sources (usually) satisfies the first condition and requiring that the group be sizable and sufficiently cohesive regarding the matter in question satisfies the second condition.
Tl;dr: the Stack Exchange system in general is not designed to properly handle most questions and answers about or from the perspective of non-traditional and/or unorthodox groups within Christianity, and there's not much we can do about that.
For the most part, such "dogma free" groups are like unicorns: everybody seems to know what they look like but nobody can prove it. In the case of questions specifically about such groups:
The group in question should exist. The relevant posts should include some reference showing that the existence of such a group is widely recognized. One loony who self-proclaims to be a member of a group that isn't otherwise acknowledged to exist does not a valid question make.
Answers about such groups should still represent real expertise on the matter. "I feel like..." or even "I'm a member of group χ and I believe..." is not a proper basis on which to answer. If you don't know about the beliefs of people outside yourself and aren't qualified to speak on behalf of the group, don't answer. If you can make statements based on your knowledge of the group that are representative of the whole AND can include reasonable reason why there can be no other references for that group, then answering from experience is fine.
Selfies are discouraged. In spite of the usual SE allowance for self-answered questions, the risk of filling the site up with propaganda in this case is much higher than for well known question scopes. If you are the only one that even thinks to ask a question about a group nobody else even knows of and it just so happens that you are the only one in a position to answer, then by posting you're basically turning the site into a soap-box to give your group a platform it wouldn't otherwise have. We're not here for that and it won't be well received.
Like all answers on this site, those specifically from the perspective of such groups don't belong on either general-overview questions or questions specific to other groups. Only questions specific to the group questioned are call for.
A group may not have a formal creedal statement, but they're all going to have some kind of base belief system. A church with no common belief system would quickly collapse on itself. It may be the case that for these groups the evidence is clearer about what they reject than what they affirm, but that's still something we can work with.
I agree with the above answers and remarks. I just want to add that there may be sociological studies done on these types of Christians. However, these types of studies will be more focused on the sociology of these Christians rather than exploring any theology. In that light, it may be possible to detect a pattern in the population and ask a question about that, even though the religious leaders of that denomination will probably deny it or undermine it or contrast it with evidence that Person X in their congregation does not believe that way, and there is no shame or ostracism in that. I can certainly tell you that the approach is not what Martin Luther had in mind. Martin Luther would probably say that correct theology is the true praise of God.1 I can't speak for Lutherans or Lutheranism, though, partly because that's a large group of people with differing opinions, and partly because Lutheran opinions may not reflect Martin Luther. Times change, people change.
What is the prescribed way to handle indefinite boundaries? Case in point, unitarian universalist. They might call themselves 'Christan', but no christians I know would.
There are two different issues in the question as being discussed.
First, there are groups that have little defined structure, may not even be orthodox, but are non-traditional churches which still hold the core tenets of Christian faith. These can be discussed as groups on the basis of what they do define. There could be no other discussion, clearly, as anything beyond that would not be pertaining to the group as a whole. There can be no group which defines nothing. Even if unspoken, it would be 'tohu vo bahu' (formless and void, Gen 1:2). Nature abhors a vacuum, and it would either create rules, spoken or unspoken, or collapse in on itself.
But the second issue here is the churches which violate even the basic fundamentals, which most Christians would reject fellowship with. UU churches are not considered Christian by any I know, nor are mormon (im talking about in the eyes of Christians I know), as are others. Further, there are groups which are rapidly departing orthodoxy. Whether or not they have left, though, is a truth statement. But, many groups (thinking of those like Rob Bell), have left many fundamentals, and dont seem to want to have anything to do with what is commonly called Christanity, except in name only. How far will they go?
I am not making a 'truth' statement here, but whether his or another group has gone fully beyond the limits of 'Christianity', the point is (a) there is a limit, and (b) some people have and are going beyond it. And, whether they have or not is a truth statement.
If someone came in saying they were Christians but only keeps the basics of the faith, that is one thing. But, when the fundamentals of a group, by whatever name, contradict the definition of Christian (to most, that is, as it is 'subjective'), to the point of onerecent question asking if Jesus of Nazereth was just a goid idea later written down (not a person), what prevents a site such as this from degrading into to the same chaos as Genesis 1:2, above? If it is simply up-and-down votes, its in trouble!
It's one thing to simply be unorthodox. Its another entirely when people begin to ask questions further and further out. In all honesty, it seems if there was a "universalism.SE", you could direct the later group of questions there, while focusing discussion of the former on what such groups do or do not define, and how that compares to what is written in the Bible or how it compares to orthodoxy (both non-subjective, until intrpretation and opinion enters). But, doing so, of course, would introduce a value decision of its own, wouldnt it? (Which, of course, is fundamental to orthodoxy that it do so).
As a case in point, a ministrer I know and myself have his decision that he was no longer going to agree with the Bible as an authority. He had made some interesting claims already, to which I disagreed, and, when he finally went public with the notion that he no longer considered the Bible authoritative, I was relieved, because, now, he is public that he considers his judgment of greater worth than the Bible (take it or leave it, its what he did). Because of that, I feel relieved, because now, at least, there is no more confusion. He is no longer saying this is what the Bible teaches, he is willingly putting himself as the authority (right or wrong), and there is now no further confusion about his teaching and orthodoxy. He has simlply left it, and now agrees, the thing had insisted all along.
