The concept of blasphemy has been the subject of considerable legal debate and normative analysis. However, we know much less about the lived realities of people living under regimes that not only criminalise blasphemy but also actively monitor and enforce blasphemy laws. This article analyses metal music as a form of religious deviance in Iran, where the production and consumption of most types of metal music have been banned. We examine how Iranian metal musicians negotiate the tension between free artistic expression and religious control and argue that the effect of control is opposite to its intention: The religiously deviant label is carried as a marker of authenticity in the scene instead. In this way, the control itself works to inspire ‘blasphemous’ acts, just as the theory of secondary deviation suggests.