Traditions dictate the lives of the people of Umuaro. Seasons are punctuated by rituals, and festivals are managed by the priests of the various deities associated with each village. The overall deity, Ulu, provides the important purification rites as well as feast associated with the rhythms of agriculture. In Arrow of God we see that these traditions are undermined by the coming of Christianity, the power of the British colonial office, and, most importantly, by Ezeulu's inflexibility and insistence on adhering to tradition. Ezeulu insists on waiting a full month to eat each sacred yam, even though that means he can't call the Feast of the New Yam for another three months. Meanwhile, the people's crops are rotting in the field and people are starving to death. The elders of Umuaro offer to take the punishment on themselves, but Ezeulu refuses. While Ezeulu is stubbornly following tradition – and punishing his people – the people of Umuaro slowly begin to starve because they are unable to harvest the crops.
Although Ezeulu claims he can't break tradition to announce the New Yam Festival, it is his stubborn pride that leads him to allow his people to suffer.
Because Christianity turns out to be a more flexible religion than it appears from the outside, the catechist is able to take advantage of Ezeulu's inability to take independent action from his deity. As a result, Christianity triumphs over traditional Umuaro religion.