The book, subtitled "Priesthood, Celibacy, and the Crisis of the Catholic Church," elicited conflicting statements on the extent of the pope emeritus's involvement in the project.
Sarah defended himself in statements on Twitter, saying Jan. 17, 2020 he met with Benedict and "there is no misunderstanding between us."
The book contains a chapter credited to Benedict, a chapter credited to Sarah, and an introduction and conclusion, which have been attributed to the two men jointly.
Cardinal Sarah was considered papabile, or a candidate for the papacy, in the 2013 conclave which elected Pope Francis.
Born in 1945 in French Guinea, Sarah was ordained a priest in 1969 for the Diocese of Conakry, after periods of study in Ivory Coast, Guinea, France, Senegal, Rome, and Jerusalem.
Sarah was appointed archbishop of Conakry in 1979, at the age of 34, a position he held until 2001, including during the dictatorship of Ahmed Sékou Touré.
Sarah has been praised for his resistance to Sékou Touré's Marxist dictatorship, and for maintaining the unity of the Church as an independent institution as Catholic clergy and laity were persecuted.
In 2001, Pope John Paul II brought Sarah to the Vatican when he named him secretary of the Congregation for the Evangelization of Peoples.
He was appointed president of the Pontifical Council Cor Unum in October 2010, and one month later he was elevated to cardinal.
Sarah was named prefect of the Divine Worship congregation in 2014.
During the coronavirus pandemic in April 2020, Sarah said in an interview with the French magazine Valeurs actuelles that the sick and dying cannot be denied the sacramental assistance of a priest.
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He said: "Priests must do everything they can to remain close to the faithful. They must do everything in their power to assist the dying, without complicating the task of the caretakers and the civil authorities."
"But no one," he continued, "has the right to deprive a sick or dying person of the spiritual assistance of a priest. It is an absolute and inalienable right."
In May last year, Sarah insisted he was wrongly included as a signatory on a controversial open letter arguing that forces could exploit the pandemic in order to usher in a one-world government.