John Kang was a fisherman in Sinchang, Chungcheong-do. He learned the catechism from his father who had accepted the Catholic faith earlier and became a Catholic. He was faithful to his duty as a Catholic and worked hard to teach and guide his children and the faithful in his village. As a result, he was appointed as catechist by Bishop A. Daveluy (Antoine An Don-i).


The Byeongin Persecution of 1866 broke out when John assisted missionaries and served the Church. So he sent his wife to a relative’s house and his 15 year old son to someone’s house as a farmhand in order to commit himself to concealing and taking care of missionaries. With his help, Father F. Ridel (Félix Yi Bok-myeong) was able to find a hiding place in Gongju and to meet Father S. Féron (Stanislas Kwon) who was not arrested. After Father F. Ridel fled to China on the instruction of his superior Father S. Féron, John took care of Father S. Féron and Father N. Calais (Nicholas Kang) who remained in Korea.


Gradually John Kang became known because of such activities. He was finally arrested by policemen from the Police Headquarters patrolling in Sinchang in 1867. The policemen found a letter from a missionary on him, so that they thought he was the leader of the Catholic community and took him to Seoul.


Before being sent to Seoul, he said to his family, “I will keep my faith at any cost, and die a martyr for the Lord. Practice the catechism in accordance with the teaching of the Lord and if you are arrested, die martyrs for the Lord.” He was taken to Yanghwajin and died a martyr by beheading along with Thaddeus Jo the catechist on August 30 (August 2 by the lunar calendar), 1867. John Kang was 67 years old.