This study presents a comprehensive historical, pedagogical, and doctrinal analysis of the Qadiani (Ahmadiyya) movement in South Asia, with particular focus on India and Pakistan. It examines the emergence of the movement within the socio-political context of British colonialism, its theological claims—especially regarding prophethood—and its long-term impact on Muslim identity, resistance to colonial rule, and contemporary understandings of Islam in non-Muslim societies. Using primary Islamic sources (the Qur’an and Sunnah), classical and modern scholarly consensus (ijmāʿ), and historical analysis, the study argues that Qadianism represents not merely a sectarian disagreement but a doctrinal rupture concerning the finality of prophethood (khatm al-nubuwwa). The research further explores intellectual, educational, and legal strategies necessary to address the spread of the movement—particularly in Western contexts—through scholarly engagement, pedagogical clarity, and institutional frameworks rather than coercion or violence.