Historically, vocation has been used in various ways, but all of them have the commonality that God calls a person to a vocational life. The meanings of Vocation that stand out are the call all Christians have to follow Christ. When Church people speak of Vocation, much more often they mean a vocation to a very specific religious life, such as the call of the priest or a nun. Catholics would speak of not only Celibate church officials as called to their life, but they also would speak of the vocation of marriage. Later, protestants popularized the idea that people could have a vocational calling to secular vocations.
Historically, those who have a sense of Church vocation would be put under Church authorities such as spiritual advisers and confessors. They would go through a process discernment which was directed by the church. In addition, they would go through a period of learning, and possibly ordination. Historically vocation was taken very seriously, and it was generally expected that it would be a lifetime commitment.
Theologians have argued some about the nature of Vocation, such as whether or not a strong urge to follow a way of life is a reliable mark of a calling. Some see a vocation as being this strong sense — while others recognize that people can feel passionately without divine intervention and that sometimes vocation can lie in areas outside of passion.
The Catholic church has a long history of third orders which represent a vocational connection with the church that is something other than spending one’s life following a vow. It allows people who are married, and working in a secular business to participate in the religious community as well. Such people would not have been clergy, or monks or nuns — but, they would have a religious vocation along with their secular vocations. These third orders would allow the people to participate in both.
Before Luther, the assumption seems to have been that vocation is a lifelong commitment. A person is, in a real sense defined by what he or she does, whether the person is called to be a miller, a baker, a shoemaker, or a priest. Luther challenged this, at least on the surface by accepting a call to the celibate life of a monk teaching theology to marry and call for reforms in the church that included allowing clergy to marry. Luther, eventually, married a former nun.
What stands out to me is that the Church has never questioned the idea of vocation, only the individual’s ability to correctly discern and obey God’s voice. Both the Roman Catholic and Eastern Orthodox church includes both celibacy and marriage as divine vocations supported by spiritual gifts. The idea that extraordinary celibacy to follow a calling still allows vocation to be special — but, it appears that the not only does the church feel that God calls people, but historically vocation is universal.