functions". Secular versus religious influences Scholarly interest continues on the extent to which inherited, long-standing, cultural-religious notions of anti-Judaism in Christian Europe contributed to Hitler's personal racial anti-Semitism, and what influence a pseudo-scientific "primitive version of social-Darwinism", mixed with 19th century imperialist notions, brought to bear on his psychology. While Hitler's views on these subjects have often been called "social Darwinist", Hitler's grasp of the subject has been argued to have been incomplete, there is little agreement among historians as to what the term may mean, or how it transformed from its 19th-century scientific origins, to become a central component of a genocidal political ideology in the 20th century. According to historian Lucy Dawidowicz, anti-Semitism has a long history within Christianity, and the line of "anti-Semitic descent" from Luther to Hitler is "easy to draw". In her The War Against the Jews, 1933–1945, she writes that Luther and Hitler were obsessed by the "demonologized universe" inhabited by Jews. Dawidowicz states that the similarities between Luther's anti-Semitic writings and modern anti-Semitism are no coincidence, because they derived from a common history of Judenhass which can be traced to Haman's advice to Ahasuerus, although modern German anti-Semitism also has its roots in German nationalism. Writers including Susannah Heschel and John Toland, have drawn links between Hitler's Catholic background and his anti-Semitism. Catholic historian José M. Sánchez argues that the anti-Semitism that led to the Holocaust was explicitly rooted in Christianity: Laurence Rees in contrast, notes that there is little emphasis on Christianity in Mein Kampf, which presents a view of the universe conspicuously at odds with traditional Christian notions long established in Germany. Hitler's vision is ordered instead around principles of struggle between weak and strong. Rees argues that Hitler's "bleak and violent vision" and visceral hatred of the Jews had been influenced by sources outside the Christian tradition. The notion of life as struggle Hitler drew from social Darwinism, the notion of the superiority of the "Aryan race" he drew from Arthur de Gobineau's The Inequality of the Human Races; from events following Russia's surrender in World War One when Germany seized agricultural lands in the East he formed the idea of colonising the Soviet Union; and from Alfred Rosenberg he took the idea of a link between Judaism and Bolshevism, writes Rees. Richard J. Evans notes that Hitler "used his own version of the language of social Darwinism as a