In almost all of his novels, Kazantzakis utilizes his storytelling to emphasize philosophical challenges. His characters openly confront existential issues: in a universe lacking inherent meaning, an individual must either forge their own purpose or wander aimlessly toward a pointless end.

In Zorba the Greek, Kazantzakis explores this existential dilemma through a series of contrasts, primarily visible in the characters themselves. The narrator, affectionately known as "the Boss," is an ascetic who attempts to escape the world's harsh realities by deeply engaging in the study of Buddhism. By a twist of fate, he enters a business partnership with the vivacious, indulgent, earthy, and womanizing handyman, Alexis Zorba. Their differing reactions to various crises and their conversations about a person's duties to themselves and others provide Kazantzakis with an opportunity to delve into themes such as the struggle between spirit and flesh, involvement versus withdrawal, and other related topics.

The novel can be understood in classical terms as a contrast between Apollonian and Dionysian viewpoints. The Boss is portrayed as thoughtful and analytical, whereas Zorba acts based on instinct and raw emotion. Although Kazantzakis does not outright advocate for the Dionysian way of life, he implies throughout the novel that asceticism alone falls short in fully appreciating the human experience. To be genuinely human means to embrace both physical and intellectual aspects; however, it is essential to master both to confront the challenging truth that life is ultimately shaped by one's own actions.