The person making the argument to this man, that God is "not knowable", was perhaps over emphasizing the point to make a point. First, I don't believe this person really understands Orthodoxy very well (and perhaps Islam).
In fact, Orthodox Christians may not "know God" in a certain sense, but we do know enough to spend our entire lives trying to be like Him, like Christ. It is this struggle to be like Christ which completely separates us from any resemblance of Islam. For instance, one aspect of be Christ-like is to be passionless. Islam on the other hand teaches the opposite in many respects, and this is such an important aspect by itself that it immediatley creates such a huge difference that any other "similiarity" could only be slight. But a Protestant (the author?) probably doesn't know about any kind of struggle toward passionlessness.
So it is true enough that I could draw many comparisons and similarities between an apple and an orange, but it would be quite presumptuous to say a person doesn't like apples because of all the similarities of an orange. Of course, the comparison between Orthodoxy and Islam is more appropriatly drawn with an immeasurable treasure and a pile of dung ( and yes, to you socio-political correctopaths, I did mean to insult the invention called Islam; and I realize I might be risking my life.
). Orthodoxy is all about Christ's love for us, and our love for Him the path that must be walked to reach Him. This path is so much different than Islam that one would have to be very ignorant about Islam and/or Christianity (Orthodoxy) to say or think otherwise. Of course, many people are ignorant about Islam, which is a good thing.
So I think the article may sound "academic" but is really quite foolish.
Islam is such a sick and demented religion that I cringe to think anyone could say it even remotley resembles Orthodoxy. That is my opinion anyway.