Yes, while I ascribe to "Closed" questions as being "Off Topic", these are not always evident at 1st glance.
Take for example the question in point: A Scripture was used to compare to the teachings/persona of Islam.
There have been several "On Topic" questions as relating to Islam See This and they have evoked some very excellent answers(See Here). If the Question Starts from the Text, and can be Answered By the Text, then it is OT/OH, despite the reservations of those who are 'uncomfortable' with the topic.
Now, if the question was merely about the teachings or tenents of Islam, then it is for another site, not ours. This also holds true for Jehovah's Witnesses, Mormons, Roman Catholics, or Free-Will Baptists. Since our Site Directives are specific about "Questions Regarding Theology" as being "Off Topic", then the same rule applies to ALL!
However, it has been debated frequently, and needs further mentioning that our "Understanding of Scripture" informs our theology. So, for a Roman Catholic who merely wants to debate "Apostolic Succession", this is certainly "Off-Topic"; but if he quotes Matt. 16:18 as his basis for the Primacy of Peter, then the question is entirely ON TOPIC, with the reference being given to how we understand that passage, in light of Apostolic Succession.
I realize the "Let's not go there, and prevent controversy" camp gets squeamish when I mention these things, but this is how we maintain relevancy(and get out of "Beta") by answering the Difficult Questions-Within Our Site Directives!