What is the reasoning behind a nun or sister choosing a religious name? Where does the significance come from? How is a religious name determined?
In the Catholic tradition as well as in many other religious traditions and cultural traditions, the taking on of a new name is symbolic of entering into a new place in one’s life. In Scripture, there are many times when a person takes a new name. For example, Abram was given the name Abraham and Sarai the name Sarah (Genesis 17) to indicate that God had called them to a new place in their relationship with God and in their role in human history. Jesus called Simon to follow him and gave him a new name: Cephas which translates to Peter (John 1:42).
Taking on a new name is also common in our Catholic sacramental tradition. When a person is baptized or confirmed, she or he takes on a new name symbolizing the new life they have entered into.
There are a variety of customs across religious congregations as to how a religious name was assigned. Some new sisters were allowed to suggest their name preference but it was ultimately up to the superior of the community or another leader to decide upon the name. The name typically had to be a saint’s name or a title of Mary or Christ. In congregations that are named after Mary, it was common that all the names include “Mary” as the first part of a sister's religious name.Sisters might also suggest as their preference a favorite saint or the saint that their parish was named after or the name of a parent (if it were also a saint’s name). In other cases, sisters were simply assigned a name — sometimes it was the name of a sister who had died in the congregation.
Many religious communities required and continue to require new entrants to take a new name as a sign of their new life as a religious. Other communities allow a person to keep their baptismal name since our vocation is intimately linked to our baptismal call.