What is the author's style in Saint Emmanuel the Good, Martyr by Miguel de Unamuno?

Unamuno coined the term "nivola" to describe his style of writing. He considered a nivola to be a work of fiction, in which the setting and events of the plot are less important than the ideas expressed by the characters. "Saint Emmanuel the Good, Martyr" is an example of Unamuno's concept. In this story, the characters are portrayed in terms of their spiritual struggles. Thus, the story's central theme of religious and philosophical questioning comes to the forefront, and the story's characters are left undeveloped outside of their expressions in regard to religious faith or doubt.