In a Facebook comment about my earlier post, one of my friends noted that many Old Testament figures practiced fasting and went on vision quests, as did Jesus and John the Baptist. He was, of course, absolutely correct. There are many historically documented examples of shamanic practices in the pre-Christian Levant. They show that these techniques were used in sophisticated urban cultures, not just among nomadic and hunter-gatherer tribes.
But they also show the tensions between the Shaman and the Priest - between the visionary and the religious organizer - existed long before Christianity. The founding fathers of Judaism may have spoken directly with G-d and conveyed his message, but they paid a heavy price for that privilege. Tradition holds that most if not all of the Jewish prophets were martyred. (And of course we all know how things turned out for Jesus and John the Baptist... ).
Insofar as Shamans acts as a direct conduit between the people and the Divine, they are dangerous. They are not working from a script and so their message is unpredictable. The gods may criticize kings and commoners alike: they may warn of lean times to come when you'd rather hear of prosperity. And so the shamanic office becomes co-opted into an official structure. Access to the oracles is strictly controlled: those officials who need to know of impending dangers can be warned while the populace is left blissfully and safely ignorant. Officially sanctioned liturgies preserve a culture's heritage - at least the officially sanctioned version thereof.
The Shaman (a problematic but useful term: more on that later, with a nod to my friend Hugh Eckert) comes from hunter-gatherer, nomadic and rustic cultures. The Priest is a product of the city-state and the empire. Belief in the Gods remains, but access is limited to those who are born to power or who are able to purchase it. The two roles need not be mutually exclusive. For every wealthy man who sought counsel at Delphi, there were innumerable others who consulted local oracles or healers. So long as the Shamans kept out of the way and posed no threat to the greater authority (whoever that might be this decade), they were tolerated in the way urban folks tolerate the rural: pious if unwashed and superstitious rubes.
As urban and imperial cultures develop, the Priest is seen as an ideal while the Shaman is scorned as primitive, uninformed, and unenlightened. When the empire lands on foreign shore, the Shaman becomes a frightening enemy, one whose connection to the Gods is as strong as or stronger than the Priest's. In time the Shaman becomes the Witch Doctor, a caricature with a bone through his nose and a bevy of bare-breasted wives by his side: a figure of mockery tinged with fear. But for most of history the mad visionary who wandered in from the wilderness with a vision was not likely to receive a warm welcome from the palace or from the temple establishment. It was a high risk job whose rewards, if any, were unlikely to be found in this lifetime.