To speak prophetically, according to one contemporary usage, is to address the current ills and injustices of society from a courageous, if not also from a somewhat unpopular point of view when judged by those content with he status quo. Therefore, since the Old Testament prophets were known for some similar types of outspoken challenges in their day, they have emerged in modern times as the exemplars of all who would buck the system and speak forthrightly against the prevailing current of thought in society.
Frankly, there is more than a modicum of truth in this picture. The prophets were indeed revolutionaries of a sort, yet they would hardly fit easily into all the modern equivalents of the roles that have been cast for them. For example, to name one huge disparity between those Biblical prophets and their aspiring modern counterparts, the Old Testament prophets did not make their primary appeal to the structures or institutions of their society, but to the individuals who made up those communities and institutions. What is more, the lever they proposed to cause a revolutionary turnabout was the Word of God itself rather than direct sociological tinkering or political agitation. Thus, the Old Testament prophets were revolutionaries who did indeed hate with a passion every form of oppression, injustice, and unrighteousness, but they viewed these ills as being mere symptoms of deeper spiritual problems which cried out for each individual to respond to the declared Word of God.
Walt Kaiser, Toward an Exegetical Theology, 185-186