Though Sidqi took a distinctive approach – he was not a typical Islamic thinker – his book's argument was not unique but reflected a widespread trend in Arab rejections of Nazism.[38] His polemic was based on a thorough familiarity with Hitler's Mein Kampf, the writings of Alfred Rosenberg, and broadcasts of Nazi propaganda by Joseph Goebbels. He compares the ideological material in these sources with Islamic classical texts ranging from the Qur'an and the Hadith collections to modern writings, including works by Muhammad Abduh, Jamal ad-Din al-Afghani and Mustafa Kamil.[37] The fundamental element that renders Nazism not only incompatible with, but inimical to, Islam, Sidqi argued, lies in the former's concept of racism (al-'unṣuriyya/al-'irqiyya).[37]