Edith Stein was born October 12, 1891, into a Jewish family. However, by the time she reached her teenage years she had become an agnostic, doubting the existence of God.
As she became a young adult, Edith went on a pursuit of the truth, primarily through the study of modern philosophy.
Providentially she stumbled upon the Autobiography of St. Teresa of Avila.
The Vatican biography of her life explains how she came across this book.
It was St. Teresa's book that took her further into the arms of the Catholic Church.
She was baptized on January 1, 1922, and according to some sources, she took "Teresa" as her baptismal name.
Shortly afterwards Edith entered a Carmelite convent and at her investiture on April 15, 1934, she took the religious name of "Sr. Teresa Benedicta of the Cross," to honor St. Teresa of Avila and St. Benedict of Nursia.
St. Edith or St. Teresa?
With the rise of Hitler and his Nazi regime, Sr. Teresa was taken from her Carmelite convent because of her Jewish ancestry. Even though she was a baptized Christian, she was still sent to Auschwitz because she was born into a Jewish family.
There she died in a gas chamber.
When the Church canonized her in 1998, St. John Paul II used both names to refer to her, as she was Edith Stein for most of her life and "Sr. Teresa" for only a few years.
Officially she is known on the liturgical calendar as, "St. Teresa Benedict of the Cross."
However, this does not mean that we can't refer to her as "St. Edith Stein," since the name refers to the same person, similar to how "St. Padre Pio" is not his "liturgical name," but is is "common" name.
