The southern entrance to the cathedral was guarded by two portraits painted on the outside walls, the depiction of St Mercurius on the right side, and the portrait of an archangel holding a sword on the left side. Mercurius was a Roman soldier who died a martyr’s death in the second half of the third century AD, during the oppression of Christians at the time of the reign of Emperor Decius.
The artist presented the saint riding a horse, in the act of spearing a tiny figure tread upon by the horse. The prostate man, bearded and wearing white robes and a crown, has been identified as the Roman Emperor Julian the Apostate.
The figure of Mercurius is involved in numerous legends recounting his acts as well as miracles after his death, when, as a saint, he descended from Heaven to kill the Emperor. Julian the Apostate, though baptized, oppressed the Church and intended to restore the cult of pagan idols in the Roman Empire. He was murdered by an anonymous assassin in AD 363 during a military excursion to Persia. His death reverberated in the Empire, provoking many comments and speculations. Christian writers expressed conviction that a punishment from Heaven reached the apostate.
Another motif from the legends concerns the encounter of young Mercurius, a private in the Roman army, with the Angel of the Lord during a military excursion against the barbarians. The Angel, whom Mercurius believed to be a high official of the imperial court, handed him a sword. Due to the powers of the miraculous sword, Romans effortlessly defeated the enemy. To commemorate the event, Egyptian Christians gave the saint the nickname of ‘Abu Seifen’ – the ‘Father of Two Swords’. This episode could have inspired the other painting with the angel holding a sword.
On the walls of Nubian churches there were many depictions of warrior saints, often presented as riders defeating demons in human forms. The sainted warriors embodied knightly virtues, particularly esteemed among army officers and soldiers.