He explains that a nation’s religion is inextricably linked to war and that religious differences make people irrational to the point of extreme violence. He comments on the ever-increasing importance of religion in forming a close-knit family, community, or nation. He implies that people’s thoughts are usually directed by their religious persuasion and comments on the fact that humans seem to need religion as a moral compass.
His comments were meant to criticize the petty conflicts in Europe that were usually due to religious differences and which resulted in countless deaths. Indeed, Swift considers that the inevitable result of religious differences is death and destruction since they stem from abstract notions that can never be reconciled because they are immaterial, although the consequences are very material.