A martyr of Karnu in Georgia, commemorated by the Church though no detailed life survives.
The Holy Martyr Isaac of Karnu
Isaac of Karnu is a Georgian martyr commemorated in the Orthodox calendar, in most sources together with his brother Joseph as the New Martyrs Isaac and Joseph of Georgia. The synaxarion places the brothers in Theodosiopolis, the city the Georgians called Karnu (also rendered Karin), and recounts that they were born into a Muslim household yet were raised in the Christian faith by their mother.
According to the account preserved in the Lives of the Saints, the brothers refused repeated demands to renounce Christ and were put to death by beheading. Isaac is commemorated on August 16; the joint feast of the two brothers is also kept on September 16.
The synaxarion relates that Isaac and his brother Joseph came from Theodosiopolis, known to the Georgians as Karnu. Their father was a Muslim, but their mother was a Christian who, by tradition, secretly instructed her sons in the Christian faith.
Their devotion is said to have grown to the point that they traveled to Constantinople to seek permission to settle there from the Byzantine emperor Nikephoros I, who reigned from 802 to 811.
By the account preserved in the Lives of the Saints, the emir of Theodosiopolis learned of the brothers' Christian confession and pressed them to return to Islam. Their elderly father joined the emir in urging them to renounce Christ, with promises of honor on the one hand and threats of torture and death on the other, but the brothers held firm.
The emir ordered their execution, and they were beheaded. The same source relates that their remains shone with a radiant light during the following night, so alarming their persecutors that local Christians were permitted to bury them with honor; a church is said to have been raised over the burial place. Georgian tradition dates their repose to the year 808, though the Orthodox Church in America's English life does not itself fix the year.
Isaac is listed under August 16 as 'Martyr Isaac of Karnu, Georgia,' alongside his brother Joseph and other Georgian saints of that day. The brothers are also commemorated jointly on September 16 as the New Martyrs Isaac and Joseph of Georgia, where the fuller narrative of their lives is preserved. Proper liturgical texts are appointed for the August 16 commemoration.
Honest stub; OCA gives no life details.