Shikand-gumanig Vizar is a Zoroastrian theological work written by Mardan-Farrukh, the son of Urmuzd-Dad. The book outlines the principles of Zoroastrianism and then cast doubts about certain Islamic, Jewish, Christian, and Manichaean doctrines. The main problem, according to Mardan-Farrukh, is that of identification of the origins of the good and the evil, which is closely associated with the problem of monotheism. Thus, the author cites and then criticizes passages from the sources of Abrahamic religions. In fact, the author tries to show that the good and the evil cannot possibly issue from one and the same origin. Thus, prior to the creation of the world, Yazata (or God) had a combative rival responsible for the evil in the world. Mardan-Farrukh presents two general arguments for the existence of such a rival. First: if Yazata had no rival, then the creation of the world would be purposeless; and second: the existence of the good and the bad in the world is evidence of the existence of two essences, since two conflicting effects cannot be attributed to one and the same substance. In his view, the world was created because the rival had invaded in the illuminated world. Thus, the creation of the world can only be justified and be deemed wise if this thesis is true. Otherwise, we need to answer three questions: first, what is the relation between evils and divine wisdom? The issue of prophethood arises under this question. Second, what is the relation between evils and divine justice? And third, how could conflicting attributes be ascribed to one and the same Yazata?