In accordance with the contents of several Quranic and Sunnah statements, not only curst upon people proved to be lecher or infidel is legal, but, in some cases, it also is essential. Unlike some Sunni jurisprudents suppose, this curst is not legal only upon such people’s nature or characteristics. In mentioned verdict, of course, one must observe whatever essential for maintaining unity among Islamic sects; this is due to different perspectives about correctness of rituals and beliefs among those sects. What, according to idea of a sect, feature implying deviation and infidelity of a person is proved? According to Islamic jurisprudence and Jafari jurisprudence in particular, can the obligated person, reciting reasons, do curst upon that particular person? Maintaining Islamic system depends on maintaining Muslims’ unity, and this will not be accomplished by neglecting the respect of any Islamic sect toward the sacred issues of other Muslims; therefore, by emergence of a secondary title, offense or insult, even in the form of curst upon the lecher and infidel people respected by a sect of Muslim is not legal and curst in such cases must contain general titles without naming special people.