What, is it illegal to think now?
In muslim dominated countries, yes it is. At one time early on, there were muslim scholars and they were actually leading the west. Then there was a debate and it was determined that the only truth is the Koran; if there is anything in the world which contradicts the Koran it must be a lie and if you pursue it you are evil. And so around 700 years ago the golden era of Islamic scholarship we are always hearing about came to a sudden and permanent stop.
Since then Islam is only about ignorance, stagnation, and aggression.