Karen Armstrong FRSL (born 14 November 1944) is a British author and commentator known for her books on comparative religion. A former Roman Catholic religious sister, she went from a conservative to a more liberal and mystical Christian faith. She first rose to prominence in 1993 with her book A History of God: The 4,000-Year Quest of Judaism, Christianity and Islam. Her work focuses on commonalities of the major religions, such as the importance of compassion and the Golden Rule.
Armstrong was born at Wildmoor, Worcestershire, into a family of Irish ancestry who, after her birth, moved to Bromsgrove and later to Birmingham. In 1962, while still in her teens, she became a member of the Sisters of the Holy Child Jesus, a teaching congregation, in which she remained for seven years. Armstrong claims she suffered physical and psychological abuse in the convent, according to The Guardian newspaper:-
But the sisters ran a cruel regime. Armstrong was required to mortify her flesh with whips and wear a spiked chain around her arm. When she spoke out of turn, she claims she was forced to sew at a treadle machine with no needle for a fortnight. 
Once she had advanced from postulant and novice to professed nun, she enrolled in St Anne’s College, Oxford, to study English. Armstrong left her order in 1969 while still a student at Oxford. After graduating with a Congratulatory First, she embarked on a DPhil on the poet Tennyson. According to Armstrong, she wrote her dissertation on a topic that had been approved by the university committee. Nevertheless it was failed by her external examiner on the grounds that the topic had been unsuitable. Armstrong did not formally protest this verdict, nor did she embark upon a new topic but instead abandoned hope of an academic career. She reports that this period in her life was marked by ill-health stemming from her lifelong but, at that time, still undiagnosed temporal lobe epilepsy.