Pope John Paul II’s Memory and Identity claims both were the result of governments clashing with divine law. He writes that abortion and the mass murder of six million Jews both came about as a result of people usurping the "law of God" beneath the guise of democracy.
His comments have deeply upset Germany’s Jewish community, whose leaders say they detract from the enormity of the Nazi extermination programme, which stands alone in history and cannot be equated with anything else.
Paul Spiegel, the president of Germany’s Central Council for Jews, linked the remarks to statements made last month by the Roman Catholic Church’s Cardinal Joachim Meisner, comparing abortion to the repression of Hitler and Stalin.
"The Catholic Church does not understand, or does not want to understand that there is an enormous difference between mass genocide and what women do with their bodies," said Mr Spiegel.
Cardinal Joseph Ratzinger, a German who heads the Vatican’s Congregation for the Doctrine of the Faith, rejected suggestions that the Pope was "putting abortion and the Shoah [the Hebrew word for the Holocaust] on the same level". He said the Pope just wanted to alert society to the "danger of evil".
The book, which examines the damage done by Nazism and communism to Europe last century, says terrorist networks represent "a constant threat for the life of millions of innocents", and specifically mentions 11 September and other recent outrages.
It also contains the Pope’s first published account of the moments after he was shot by a Turkish gunman in 1981. He said he was fearful and in pain but had "a strange feeling of confidence" he would live.
The book was launched in Rome this week and 14 editions in 11 languages are due to be published.
The book is based on conversations the Pope had in Polish with two friends, the philosopher Krzysztof Michalski and the late Father Jozef Tischner, at the papal summer residence near Rome in 1993.