The theme of William Butler Yeats' "The Second Coming"

Hey, you have got this under the wrong work. Anyhow, there are quite a few themes. I'll mention a couple.

Theme of Warfare

World War One is still fresh in the mind of Yeats. It was considered the worst war in history. Check out the first stanza. It is fraught with images of violence and warfare. The "Second coming" alludes to the real spiritual war (Armageddon) that takes place in the Old Testament.

Class Warfare

"The Second Coming" manifests these tensions. The art of falconing refers to a discipline often associated with the noble class of medieval society.