Soldier and Confessor
The vita of Mercurius presents him as a young man of high rank in the Roman army, a Scythian by descent whose father, named Gordian in one source, had likewise confessed the Christian faith. He served under the emperors Decius and Valerian, whose decrees ordered every Roman citizen to worship the pagan gods and condemned Christians who refused.
Tradition relates that during a campaign against barbarian invaders an angel of the Lord appeared to Mercurius disguised as a nobleman and handed him a sword, exhorting him to fight bravely and not to forget the Lord his God. With this weapon he broke through the enemy ranks and slew their king, and for this victory Decius rewarded him with command of the army.
When the emperor summoned him to sacrifice at the pagan temple, Mercurius refused. He openly declared himself a Christian, cast down his military belt and cloak at the emperor's feet, and renounced all the honors he had received in the army.
Martyrdom
After his confession, Mercurius was subjected to severe torments. The synaxarion relates that his torturers stretched him between four pillars and lit a fire beneath him and cut his body with knives, but that he was miraculously healed of his wounds.
Remaining steadfast and continuing to refuse sacrifice to the idols, he was finally beheaded at Caesarea in Cappadocia at the age of twenty-five.
Relics and Veneration
By tradition the body of Mercurius emitted a fragrance like myrrh and incense, and many of the sick were healed at his tomb. He is numbered among the great-martyrs and warrior-saints of the Church and is commemorated on November 24 in the calendar followed by the Orthodox Church in America, and on November 25 in Greek usage.
Greek accounts add that he was handsome in appearance, with blonde hair and a natural redness in his cheeks.
Traditional Accounts
A widely repeated tradition connects Mercurius with the death of the emperor Julian the Apostate. According to this account, Saint Basil the Great prayed before an icon depicting Mercurius as a soldier; the image is said to have vanished and then reappeared bearing a bloodied spear, at the very time that Julian died of a mysterious spear wound during his Persian campaign, reportedly crying out, 'Thou hast conquered, O Galilean!' This is recounted as pious tradition rather than documented history.