The site has been inundated with posts by some apparent Muslims such as Jakub Žitný, and professed Muslims such as Wilson whose questions are clearly designed to begin a dialog in which they argue about the validity of Christianity and Islam (Quran)?
Whether or not we agree with the perspective of the poster, do not make it about that. We don't care if they're Muslim, atheist, Christian, or if they worship watermelons.
The existing site guidelines for asking questions are all we need to close down questions that are designed to spark debate or argue validity of points/views.
The same goes for answering. Or rude/argumentative/hostile, or otherwise unacceptable behavior.
The obvious exception is the ones that are asking for a non-Christian view, which are still covered in the guidelines: It is off-topic because it is asking for a perspective other than a Christian one, and can be closed as such.
There's also this valid close reason:
General philosophical or sociological questions are off-topic unless clearly asking for a doctrinal answer.See: On-topic and constructive examples.
Again, don't get lured into arguing the validity of any given point. Be consistent. Hold firm to the main purpose of the site. Getting drawn into debate in comments isn't constructive, and sticking to the guidelines prevents the person in question from accusing us of bias. If we are all closing ***any**** opinion-based question (Christian view or otherwise) we can shut down argumentative/non-constructive content in such a way that is fair, consistent, and doesn't open us up to the charge of bias.
Remember, also, that our aim should not be to shut down participation, but to help others learn how to participate constructively.
With that in mind, it is fair to vote down questions, leave polite comments explaining the guidelines, flag down the moderators, or (if you're so inclined) take debates to chat, where such debate is allowed.
One final thing.... Experienced members should know better than to get drawn into debate. I'm appalled by the activity on Was Muhammad sent from God or the opposite?
Not only should that have been closed outright, but some experienced members debated on every answer, something expressly addressed in our guidelines. One answer had over 30 comments back and forth. That type of debate, again, is fine for chat, but not the main site. It's unprofessional, not constructive, and not welcome.
If the question asks for a Christian teachings concerning Islam or can be edited to do so, then it may be a valid question.
If the question assumes a Muslim view, then we flag or vote to close as off-topic and refer them to the Islam SE site (via comment) with an explanation of why the question is off-topic here.
I've seen many good questions and answers on here from Athiests. I don't believe we should pre-judge one's question based on our knowing their beliefs. I've had several questions and answers read into too far because I'm a Freemason - and some of my original questions were antagonistic.
This is a secular SE for learning and teaching (in that order) about Christianity. We cannot assume that we (as Christians) know all that there is to know about Christianity - else we wouldn't need this SE at all. However the questions need to be scoped within the context of Christianity. Therefore, "Was Muhammad sent from God or the opposite?" is a horrible question for two reasons. One is Muhammad was after Jesus, so what definitive answer could we give? The other is, it is not our job to judge.