Hazrat Khidr (pbuh) would not let any adverseness against Islam and Hazrat Mahdi (pbuh)
Excerpt from Mr. Adnan Oktar's Live Interview on A9 TV dated December 13th, 2011
ADNAN OKTAR: "Master, it might be because of the green color on you but tonight when we look at you Hazrat Khidr (pbuh) comes to mind the most, Masha'Allah. You have not been telling us about Hazrat Khidr (pbuh) for a while now. Would it be possible if you could tell us about the activities of Hazrat Khidr (pbuh) in these days? You would know better insha'Allah."
He [Hazrat Khidr (pbuh)] plays a trick on those who fall afoul of Mahdi (pbuh), of Islam; those who fall afoul of the Union of Islam. He gets them into troubles, he crashes their heads [intellectually]. Let me not mention the methods he adopts [while doing this]. I mean he crashes the heads of all those vermin wherever they are, insha'Allah.