Nichiren Daishonin answers a "reasonable question"

"Question: If, as you have stated, the benevolent deities inflict punishment on this country because it does harm to the votary of the Lotus Sutra, then epidemics should attack only the slanderers. Why is it that your own disciples also fall ill and die?
Answer: Your question is reasonable. Nevertheless, you are aware of only one side of the situation and not the other. Good and evil have been inherent in life since time without beginning. According to the provisional teachings and the schools based on them, both good and evil remain in one’s life through all the stages of the bodhisattva practice up to the stage of near-perfect enlightenment. Hence people at the stage of near-perfect enlightenment or below have faults of some kind, [but not those at the highest stage]. In contrast, the heart of the Lotus school is the doctrine of three thousand realms in a single moment of life, which reveals that both good and evil are inherent even in those at the highest stage of perfect enlightenment. The fundamental nature of enlightenment manifests itself as Brahmā and Shakra, whereas the fundamental darkness manifests itself as the devil king of the sixth heaven. The benevolent deities hate evildoers, and evil demons hate good people. Because we have entered the Latter Day of the Law, it is natural that evil demons should be everywhere in the country, just like tiles, stones, trees, and grasses. Good demons are few because sages and worthies are rare in this world. One would therefore expect to find more victims of the epidemic among Nichiren’s followers than among the believers of Nembutsu, or priests of the True Word, Zen, and Precepts schools. For some reason, however, there is less affliction and death among Nichiren’s followers. It is indeed mysterious. Is this because we are few in number, or because our faith is strong?"