Why the Charlie Hebdo attack is not about images or free speech (COMMENTARY) – Religion News Service.

Regarding images: Muhammad is a powerful symbol for Muslims. The Quran calls him a “beautiful role model,” and he is considered to be the most perfect Muslim.
It is generally accepted by Muslims that images of Muhammad, or any other person, do not appear in mosques.
However, this ban does not extend outside the mosque. Various Muslim cultures show a comfort with painting and figural representation. Images of Muhammad, his family, prophets and other holy figures exist. They are on display in museums throughout the world. In some, the faces are obscured, but in many, the faces are on full display.