Trouble understanding the the primarily opinion-based close reason in the context of this site seems to be trending today. Let me see if I can clear a few things up in regard to it. First lets take a look at the stock copy:
Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.
Please note that this is just stock copy used across over a hundred sites on the Stack Exchange network. Some of these sites are technical, some are scientific, and a handful are religious (this one as well as Judaism and Islam). There are a few other categories as well, but my point is there is a huge variety of subjects that share the same generic set of close reasons.
So the question becomes:
"What do we mean when we use that close reason here?"
There are a huge variety of theological traditions represented on this site. The only filtering going on for something to be topical here is that the doctrinal teaching has to come from an established group that uses the name 'Christian' to define themselves. This means that we very definitely do not share any common creeds or beliefs.
Incidentally even "The Bible" is not useful as an authority here. I personally very strongly believe that the Bible is the final authority for all things doctrinal. In this I subscribe to the Westminster Confession of Faith which puts it like this:
IV. The authority of the Holy Scripture, for which it ought to be believed, and obeyed, depends not upon the testimony of any man, or Church; but wholly upon God (who is truth itself) the author thereof: and therefore it is to be received, because it is the Word of God.
X. The supreme judge by which all controversies of religion are to be determined, and all decrees of councils, opinions of ancient writers, doctrines of men, and private spirits, are to be examined, and in whose sentence we are to rest, can be no other but the Holy Spirit speaking in the Scripture.
However there are two problems faced by this site that my agreeing with that confession does not solve:
Not all 'Christian' traditions believe this.
However wrong you and I may think they are, large swaths of people do not believe the Bible to be infallible, inerrant, or sufficient in its teachings. This site is about those other traditions too.
The Bible itself needs interpreting.
This is a tough pill to swallow, so allow me to come back to this...
How do we resolve these issues?
Most crucially, we have some limits in place for questions. Rather than asking about all of Christendom and it's related heresies, we require that questions have a limited scope asking inside of specific theological traditions or otherwise reducing the potential scope of answers to subset that can be reasonably answered in this format. We have some other guidance on the matter of questions on this meta site. This post is particularly important:
What makes a good focused question?
Another way of putting this is that we don't handle truth questions. This might seem counter intuitive given the fact that Christianity is all about truth. The tricky part for now folks to grok is that this site is about Christianity as a thing in itself, _not about the things that Christianity is about.
This is easier to see in answers than it is in questions.
Answers we like to see appeal to established teachings rather than to "truth".
Lets try an example on for size:
Q: Who should preside over a Sunday service?
A: All believers are priests and have equal standing in the eyes of God, services should be a a collective effort between all participants. The systematic rituals of the Old Testament have been abolished and all are free to worship as they see fit.
A: The ordained minister or elder should preside over services, directing the people as they join corporately in worship and maintain order according to Scriptural principles seen in both the Old and New Testaments.
A: Sunday is the wrong day to be worshiping. In should be Saturday in keeping with the Jewish Sabbath established it the Old Testament. Modifying it after the Resurrection as a day of celebration was a mistake.
Do you see where that is going? Nowhere.
Of course I have an answer I believe to be true, but that doesn't mean all Christians agree with me. This is what we sometimes call a "truth question" and do not like to see on this site. These often get closed with the primarily opinion-based close reason, not because there are no good answers but because it is not specified whose good answers are being sought.
Here is an example of a question that is not primarily opinion-based:
Q: How do Quakers manage their worship services?
A: Quaker worship services begin when the first person enters the room and takes a seat. Everyone is expected to enter reverently during a period known as "expectant waiting". […] Spoken messages may occur many times during a meeting, or there may be none at all. Such a message is delivered by an individual, but is understood to be coming through that person from God. […] At the close of worship, someone will signal the end by shaking hands with a neighbor. (source)
Do you see how that question is definitively answerable in a way that the last example is not? I am not a Quaker, but with a little research I could verify that the answer is indeed representative of that groups beliefs. Whether they are true in an absolute sense of God's will for worship is beside the point. The question is not about what is absolutely right or wrong, but about Christianity. It is now verifiable in a way that the first question is not.
This is what we mean by NOT being primarily opinion-based: answers are derived directly from extant Christian teachings and it is unnecessary to solve the mysteries of the universe to verify them.
Cue inevitable objection about the Bible being the authority...
I already started this topic by stating what I believe about the Bible, so please don't take this as a cop out wishy-washy answer. I have a higher regard for the authoritative nature of Scripture than the majority of people contributing to this site. The hard hard fact is that Scripture is not unambiguously clear on all points, and even the points it is clear on are only clear in the context of several significant presuppositions that not all people professing the term 'Christian' make. It is my belief that it is only with the help of the Holy Spirit that we can discern truth from its pages. Not everybody discussing it and even using it has this advantage. Additionally even those of us that do are still partially blinded by our own sinful natures and often DO get it's interpretation wrong. Even when we aren't blind and have the right help, it takes some care to rightly handle the word of truth. There is a whole field of study devoted to the analysis and interpretation of the Bible, Hermeneutics, and there is even a Stack Exchange site devoted to that field.
In the context of a church and the lives of Christians, it is proper to search out the truth of all matters and seek to understand and apply the Scriptures rightly. That is not what this site is for. This is not a church. We are not even all Christians here. This site is about the convoluted social and religious entities that call themselves 'Christian'. Use it for learning about the various branches of Christianity, but not for learning how to be a proper Christian.