John Gill defends the ancient practice of baptism by immersion against Mr. Matthias Maurice's claims that it is not scriptural. He critiques Maurice's arguments, highlighting the importance of scriptural evidence and the historical context of baptism as performed by John, Christ, and the apostles. Gill emphasizes that the original Greek word for baptism signifies immersion, and he provides various biblical examples to support his stance. He also addresses the theological implications of baptism, asserting that it represents the death, burial, and resurrection of Christ. Ultimately, Gill argues for the necessity of immersion as the proper mode of baptism, countering Maurice's assertions with scriptural and historical evidence.