An important early letter was published, probably without Montagu's consent, titled "The Genuine Copy of a Letter Written From Constantinople by an English Lady" in 1719. Both in this letter and in the "Turkish Embassy Letters" more broadly, particularly in the letters about the scholar Achmet Beg, Montagu participates in a wider English dialogue on Enlightenment ideas about religion, particularly deism, and their overlap with Islamic theology. Montagu, along with many others, including the freethinking scholar Henry Stubbe, celebrated Islam for what they saw as its rational approach to theology, for its strict monotheism, and for its teaching and practice around religious tolerance. In short, Montagu and other thinkers in this tradition saw Islam as a source of Enlightenment, as evidenced in her calling the Qur'an "the purest morality delivered in the very best language" By comparison, Montagu dedicated large portions of the "Turkish Embassy Letters" to criticizing Catholic religious practices, particularly Catholic beliefs around sainthood, miracles, and religious relics, which she frequently excoriated. In relation to these practices, she wrote, "I cannot fancy there is anything new in letting you know that priests can lie, and the mob believe all over the world."