In my area, Islamic studies, it sort of depends on the topic. For the miraculous revelation of the Qur'an, for instance, most scholars, even those who are highly critical of Islam, are willing to refer to and accept the Qur'an as a "revelation." Historically it doesn't really make much difference whether it the Qur'an was revealed by God or an invention of Muhammad or a product of Muhammad's own subconscious or whatever. There's no need to uselessly antagonize believers and there is actually a long tradition of believing Christian academics recognizing that the Qur'an may have been divinely inspired, however heretical that may be.

It's a bit different for something like the Battle of Badr where the religious accounts of the battle ascribe the Muslim victory to the sudden descent of a host of angels onto the battlefield. You'd be hard pressed to find a serious history book that gives credence to that idea, although it's inevitably mentioned in historical accounts of the battle

The European Middle Ages are jam-packed with attributing supernatural causes to events or just straight-up supernatural events--visions, miracles, devils. Medievalists tend to focus on why people might have been saying that and what the impact of that belief was. For example, we'll talk about Hildegard's visions not as though they factually, beyond a doubt were divine revelations, but from the standpoint that: at the time, they were just as good as divine revelations regardless of what they "actually" were, because everyone then believed her. And that's what influenced contemporary and future events.