What does God look like?
Yes, silly question! There was very little depiction of God in paintings, this is from Wikipedia:
For about a thousand years, in obedience to interpretations of specific Bible passages, pictorial depictions of God in Western Christianity had been avoided by Christian artists. At first only the Hand of God, often emerging from a cloud, was portrayed. Gradually, portrayals of the head and later the whole figure were depicted, and by the time of the Renaissance artistic representations of God the Father were freely used in the Western Church. Early Christians believed that the words of Book of Exodus 33:20 “Thou canst not see my face: for there shall no man see Me and live” and of the Gospel of John 1:18: “No man hath seen God at any time” were meant to apply not only to the Father, but to all attempts at the depiction of the Father.
So those were the instructions to the early Church. Early Quaker Friends went along with this in their realisation that “the word killeth”. As soon as we try to illustrate a concept with a definition, be it in words or images, we constrain it.
Western art did not feel the same constraint about illustrating Jesus, who appears in paintings throughout Christian history, which is, to me, a bit surprising. Jesus was seen as part of God, the Father, Son and Holy Ghost, and so an embodiment of God.
Our Muslim friends appear to have had a very different approach, blocking not only images of the Prophet, but also, of man. This produced the wonderful patterns and designs of the Alhambra, totally made up of abstract designs. The west just does not seem to have any respect for this very simple and understandable concept. Cartoons of the Prophet do not offend because of their content, although that may make things worse, but because they are images of what, Muslims belief, should not be imaged.