Conflict and tolerance coexisted during the Muslim rule of medieval Islamic Spain (711-1492). Islam, which successfully conquered the Iberian Peninsula in 715, destroyed most church buildings in Andalusia, Spain, and converted some into mosques. This study examines the historical process in which the basilica church was converted into mosques, and then re-converted into churches after the Spanish Reconquista. That is to say, this study analyzes the adaptive reuse of Cordoba's Mosque into a Cathedral from historical and architectural perspectives and examines the missiological rationale behind it. The following are the missiological implications and applications for today. First, the conversion of the Cordoba mosque to cathedral demonstrates the adaptive reuse of physical buildings as a place of Christian worship. Second, the Cordoba Mosque-Cathedral can serve as a bridge for dialogue and reconciliation between Christianity and Islam. Third, the Cordoba Mosque-Cathedral represents a historical legacy to foster peaceful coexistence and tolerance rather than conflict and violence.