Mallampalli begins with a discussion of South India's ancient Thomas Christian tradition, which interacted with West Asia's Persian Christians and thrived for centuries alongside their Hindu and Muslim neighbours. He then underscores efforts of Roman Catholic and Protestant missionaries to understand South Asian societies for purposes of conversion. The publication of books and tracts about other religions, interreligious debates, and aggressive preaching were central to these endeavours, but rarely succeeded at yielding converts. Instead, they played an important role in producing a climate of religious competition, which ultimately marginalized Christians in Hindu-, Muslim-, and Buddhist-majority countries of post-colonial South Asia. Ironically, the greatest response to Christianity came from poor and oppressed Dalit (formerly "untouchable") and tribal communities who were largely indifferent to missionary rhetoric. Their mass conversions, poetry, theology, and embrace of Pentecostalism are essential for understanding South Asian Christianity and its place within World Christianity today.