In some religions there are people who are called priests, presumably because they have special powers. How did this idea get started. I am particularly interested in the history in Judaism and Christianity.
"Rabbi" means teacher or leader, while "disciple" means follower or student.
Along with Judeo Christianity comes the nascence of writing down the oral tradition, certifying it as correct, and building a canon.
For the early Jews this probably peaked at about the time of the Babylonian captivity around 600 BC. Something else happened around 300 BC after the conquest of the Middle East by Alexander the Great - Hebrew died and was replaced by Aramaic and Greek. The books of the Apocrypha were written in Greek, because this was the official language of the known world after Alexander. Along with this came some innovations in Jewish religious tradition. By the time the first few pieces of the New Testament were created, Rome had become the new overlord, but Jews chose not to adopt Latin as their official language. We can speculate that the Roman desecration of the Temple at Jerusalem in ca. 70 AD is emblematic of Roman abuses that would deter Jews from embracing Latin.
"Priest" derives from the Greek word for elder - "presbyteros" which in Latin is "presbyter".
Elders would have been regarded as being the repository of all tradition. It may be that this sometimes was associated with having certain kinds of power. Early Christians would distinguish their presbyters and episcopos ("overseers") - later understood to mean "bishop" - as the church elders. This would account for the reason that Christian and Jews regard their leaders as sources of interpretation of their respective religious laws.
In any case, the central powers of a Christian priest are relegated to the rite of the mass and the sacraments. The one that seems to invoke the most sense of magic is the transubstantiation - conversion of the bread and wine in to the body and blood of Jesus. This tradition is purported to stem from the Biblical invocation to "Do this in memory of me", understood to be a command from Jesus to re-enact the transubstantiation of the Last Supper.
The reference to the Last Supper in the Bible, and the traditions that followed (having the priest perform the transubstantiation) are also connected to the rise of a Persian religion, Mithraism, in early Christian Rome. It was marked by a meal in which the food and drink were of similar sacred significance.
The other claim by early Christians was that Peter was to found the Church of Jesus after the Ascension ("upon this rock I will build my church"). It has been a long standing tradition in Catholicism that one of the duties of the founder was to establish his successor, and that this accounts for the rise of the papacy.
Priests and rabbis are also noted by their vestments. This tradition appears to have started among the rabbis, as well as many other functions, powers or duties of the early Christian priest, from blessing the congregation, rites similar to purifying the temple, and reading from the Bible.
Another characteristic of the priest or rabbi is the role of
cantor - the person who chants or sings, or leads the congregation in the prayers, incantations or hymns they use in their various definitions of worship.
A lot of western religious tradition can be attributed to the patriarchs of antiquity who have written a great deal about the reasons for various rituals as a product of their interpretations of specific Bible verses, as well as the application of logic and inference as to things they believe God intended them to do. Obviously a lot of this would be delegated to their chief promulgators of the religion, their priests.
Preachers, ministers and other leaders of the Protestant religions are not properly called priests but perform many similar duties, and would exercise some subset of the same powers. They do not call themselves priests, in part, as a way of distancing themselves from the Catholic Church.
One power or duty all of these folks have in common is the collection of tithes and charitable donations from their congregants. In part then, they have to maintain the facilities and resources of their churches, temples, prayer halls, tents and shrines, and in part they are responsible for the distribution of donations to the needy, maintenance of any affiliated clinics, hospitals or social services offices and payment of salaries to any employees they may hire.
The other main branch of the Judeo-Christian tradition is the Muslim religion, which calls its leaders mullahs or imams. Their duties and powers may be characterized as comparable to those of the Protestant preachers.
It should be noted that among Christians and Muslims the clerical leaders of high office had the power to mesmerize congregants, or invoke states of euphoria or the belief that touching their vestments restored their health or vitality or ensured their ultimate salvation. This has a parallel in the Protestant faith healers, Christian Scientists, and snake handlers.
Throughout history there have been episodes of priests, rabbis and mullahs engaging powers of the state, or taking charge of local secular affairs. In various episodes of the Christian churches this was either seen as a feature of Christian leadership and at other times it was an overt abuse of office, as in some of the bloody epochs of the Crusades and the sadistic cruelty of the Inquisition. However, in some cases the reverse was true. A "pretender" was a politico who wrested the position of the Church official and either took it for himself of gave it to his appointee. There were some 41 or 42 Catholic anti-popes. Centuries of their interference in the Catholic church probably contributed to the Protestant movements. Henry VIII stands out as an exceptional case, in that he assumed control over the Catholic Church of England after the Pope excommunicated him for unlawful divorce. He appointed Thomas More as his bishop, but executed him when More refused to acknowledge that the King could lawful acquire dominion over a church by an act of government.
Some cases of pretenders to the clerical offices of the Jewish and Moslem religions are also known. In the 1970s and 1980s there were several similar cases among Protestant leaders who turned out to be using their offices for material gain. Another case of usurpation of power took place in the Mormon church, when propaganda and bombs were used to try to take power from church leaders. The most extreme examples of pretense among Protestants were the leaders who led suicide groups, such as Jim Jones and David Koresh. Among Catholics the most serious abuses of offices were the perpetrators of sex crimes and the higher officials who covered them up. Among mullahs there is substantial evidence of tortures and killings by clerics and their secular counterparts esp. since the fall of the Shah of Iran in 1979.