One of the fundamental duties of Islamic law is to bid for good and forbid of wrong. The jurists have listed conditions for establishing the obligation; one of them is the "condition of effect". The research is based on the exploratory-analytical method and by using library sources in order to explain the Qur'anic evidence about the requirement of this condition in establishing the obligation of the mentioned duty. The hypothesis of the research is that based on the generalities and applications of the Qur'an, specially verse 164 of Al-A'raf Surah, as well as authentic traditions, this condition cannot be considered as a requirement of bid for good and forbid of wrong. In order to prove this claim, the meanings of the verses that express the following two principals have been cited: The generalities that guide us to perform our religious duty in the face of social evils and the possibility of influencing the process of preaching and warning cannot be ruled out in an absolute way. The alleged evidences of the believers have been divided into three parts: traditions, consensus and the reason decree which inadequacy of each has been proven.