The reason why a stag symbolises Christ is from the
superstition that it draws serpents by its breath from their holes, and
then tramples them to death. (See Pliny: Nat. Hist., viii. 50.)
Stag in Christian art.
The attribute of St. Julian Hospitaller, St. Felix of Valois, and
St. Aidan. When it has a crucifix between its horns it alludes to the
legendary tale of St. Hubert. When luminous it belongs to St.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894