Wahn of religion means that the religion [of Islam] to be presented as baseless and weak. The issues which result in wahn is considered forbidden. Despite its great importace, the arguments for this rule is not discussed in jurisprudential works. The present article makes a thorough study on this subject and discusses its arguments. The results show that the verse, hadiths and the intellectual argument referred to as reasons for unlawfulness of issues implying wahn, are refutable. The only reason is 'Irtikāz al-Mutasharri`ah which can be applied in two cases: the issues with no religious ruling, and multiplying the unlawfulness of unlawfull acts.