In German, the word for "faith" is "Glaube." In German, the word for "belief" is also "Glaube." Somehow in English, we've ended up with two different words for the same concept: the act of believing, or accepting that something is true. So "faith" often gets treated like an inert noun, a bit like "church" or "religion," while "belief" retains more of an apparent connection to the verb "to believe."
I think it is unfortunate that the English word "faith" isn't obviously linked to an action verb. Faith is a choice, a voluntary acceptance of something that isn't proven to everyone to the point of being considered a "fact."
This subject is on my mind because yesterday, some very bad men thought they acted on God's errand when they slaughtered the staff of a satirical magazine in France. They appear to have acted on three main beliefs: 1) Muhammed was a Prophet so holy his face can't be drawn, 2) any disrespect of Muhammed is blasphemy that merits the harshest punishment, and 3) God approves of them forcing adherence to their own beliefs in brutal ways.
Addressing these beliefs in order and attempting to do so within a framework acceptable to faithful Muslims, 1) Muhammed was drawn by good Muslims for centuries. The Quran does not prohibit drawing Muhammed. Only some hadith do, and they, unlike the Quran, are not accepted by all Muslims. If Muhammed was the last prophet, as Islam claims, then who cares if some imams a while back came up with a new restriction on permissible illustrations? Those imams don't speak for anybody but themselves because they are NOT prophets.
2) Disrespect of a cherished individual or object can be emotionally painful to see and hear (I personally never will watch The Book of Mormon musical), but it doesn't justify violence in response. Even if one follows an "eye for an eye" retributive philosophy, disrespect only justifies more disrespect in turn. Disproportionate punishments--such as execution for a mere verbal insult--is something most of the civilized world considers barbaric, and people are not bound by a book--the Quran--that they don't believe in.
Which leads me to my last point. 3) A religious movement, such as the Taliban or ISIS, that violently forces others to submit to it is an abomination in God's eyes because it removes the opportunity to choose to believe. When God--who has not even given us indisputable evidence of his very existence--tells us to believe in him, he is giving us a choice: to accept him or to not accept him. The ability to choose for ourselves is what makes faith meaningful. There is no such thing as forced faith in the same way that rape cannot be termed an amorous encounter. For that reason, I reject and oppose any interpretation of Islam/Christianity/LDS doctrine/etc. that uses violence to force others to follow it. Such violence removes the agency of a person to choose to follow God, thus destroying faith and enslaving others. (And yes, that criticism applies to some followers of the Pearls almost as much as ISIS.) Good Muslims choose to submit to God according to the teachings of Muhammed. Many people do not choose to submit to Muhammed's teachings, but they must be given the opportunity to make that choice without their survival being under threat or else the choice TO submit (i.e., Islam itself) is made meaningless. I hope that faithful Muslims promote religious movements that do not make a mockery of their own beliefs.