Protest is a form of prophecy, even when the protesters may have no religious or spiritual leanings. It's a speaking to the society about some aspect of the community that is offensive.
In the light of the Occupy protestings/prophecyings around the globe, and particularly in regard to the local one in Dunedin which for some reason has survived the trespass order set by the Mayor and Council (because the police, for some reason, have not enforced it) I found the following paragraph of interest.
A sit-in or march is not instrumental but it is significant. Even
when no immediate change in the social order can be measured, even when
persons and organizations have not yet been moved to take a different
position, the efficacy of the deed is first of all its efficacy as
sign. Since we are not the lord of history there will be times when the
only thing we can do is to speak and the only word we can speak is the
word clothed in a deed, a word which can command attention from no one
and which can coerce no one. But even in this situation the word must
be spoken in the deed in confidence that it is the Lord of history and
His Holy Spirit, not our eloquence or artistic creativity, which will
make of our sign a message.
John Howard Yoder
The Original Revolution