Purohit's essay discusses the polemical writings of Muhammad Iqbal (1877–1938) against Mirza Ghulam Ahmad (1835–1908), the founder of the Ahmadi movement. Mirza Ghulam Ahmad's vision of Islam was in many ways similar to Iqbal's: both figures were modernist and promoted renewal and reform through the idea of Muslim unity. However, Mirza Ghulam Ahmad's religious authority was charismatic: he was not only recognized as a mujaddid (renewer) but also claimed to be the masih-i-mawud (promised messiah). This article analyzes the arguments through which Iqbal denounced Mirza Ghulam Ahmad's religious authority and branded his teachings heretical. Using the work of sociologists such as Georg Simmel and Pierre Bourdieu, this piece reflects on the idea of heresy as a sociological rather than theological phenomenon—thereby calling into question entrenched theological critiques of the Ahmadis. The intra-Muslim criticisms against the Ahmadis that continue today must be examined, Purohit argues, in light of the modernist polemic against Mirza Ghulam Ahmad, exemplified in the writings of Iqbal.