To a Muslim God does not have to act rationally. If God said, worship idols and not me, then unquestionably man would have to worship idols. If God said, convert people by threats of fear and death, you don't question that you just do it. Actually I don't think the Muslims know much about God at all. They are just terrified of him. And that is what Mohammed wanted in order to keep them in line.
Astounding but true. This also explains their fatalism.
There was an excellent post a few days ago of an article discussing Islam (maybe the Crocker article?) in which the writer observed that the entire Western system is based upon the concept of natural law, even our purely secular systems, and that one of the reasons it is so difficult to install certain types of government or concepts of human life in Muslim countries is that Islam simply does not believe in natural law.
That is, "Allah" is an unpredictable, arbitrary god who is subject to no internal order or reason himself and has not established any natural order or law in the world, either. The only law that exists is the combination of ritual law and criminal law that constitutes sharia; and this is in itself purely arbitrary and exists without referrents of any kind.
My personal feeling is that "Allah" is a demon or Satan, because chaos, nihilism, and prideful isolation are characteristic of Satan as a result of his having rejected God and the order or law of God.