His themes include Greek history, religious symbolism as well as universal harmony in poems such as The Moonstruck, Prologue to Life, Mother of God, and Delphic Utterance.

During that period, Sikelianos came in contact with Greek intellectuals, and in 1909 he published his first collection of poems, Alafroískïotos (The Moonstruck), which had an immediate impact and was recognized by critics as an important work.

He also befriended fellow writer Nikos Kazantzakis, and in 1914 they spent forty days on Mount Athos, visiting most of the monasteries there and living the life of ascetics.

Sikelianos believed that the principles which had shaped classical civilization if reexamined, could offer spiritual independence and serve as a means of communication among people.

The event consisted of athletic contests (in classical fashion, reminiscent of the Pythian Games) a concert of Byzantine music, an exhibition of folk art as well as a performance of Prometheus Bound.

During the Axis occupation of Greece (1941–44), he became a source of inspiration to the Greek people, especially through his speech and poem that he recited at the funeral of the poet Kostis Palamas.

[4] In 1945 he was a founding member of the Greek-Soviet friendship union (among Nikos Kazantzakis, Nicolas Kitsikis, Yanis Kordatos, Aimilios Veakis, Ilias Iliou, Patroklos Karantinos, Athanase Apartis, George Zongolopoulos and others).