In the winter of 1777, a study gathering took placeat Jueosa (주어사,Jueosa) under the leadership of Kwon Cheol-sin (권철신). Those who attended included JeongYak-jeon (정약전) and other young scholars of the Namin faction, as well as Yi Byeok (이벽).

The group studied Confucian texts alongside newlyintroduced Western Learning books written in classical Chinese, including worksexplaining Catholic doctrine.

This meeting ignited in Kwon Cheol-sin, JeongYak-jeon, and Yi Byeok a profound desire to pursue the Catholic faith.

At Yi Byeok’s encouragement, Yi Seung-hun (이승훈) traveled to Beijing, received baptism, and returned to Korea—anevent regarded as the beginning of the Catholic Church in Korea. Thus, the faith first took root through the study meetings at Jueosa, which became the cradle of Korean Catholicism.

① Yi ByeokJohn (이벽 요한)— One of the Three FoundingFigures

Yi Byeok played a decisive pioneering role infounding the Catholic Church in Korea.

He transformed the classical Confucian atmosphere ofstudy at Jueosa into one oriented toward discovering and practicing the truthsof Christianity.

Yi Byeok introduced Catholic teaching to YiSeung-hun and encouraged him to travel to Beijing for baptism. Upon YiSeung-hun’s return in 1784, they formed the first community of Korean Catholicbelievers—a year now commemorated as the founding year of the Korean CatholicChurch.

Without doubt, Yi Byeok’s pioneering role wasfoundational to the birth of the Church in Korea.

② YiSeung-hun Peter (이승훈 베드로)— FirstBaptized Catholic and Founding Leader

Yi Seung-hun learned the Catholic faith through YiByeok.

In Beijing, he was baptized by Father Grammont,becoming the first Korean to receive the sacrament of baptism.

In 1784, he baptized Yi Byeok, Jeong Yak-jeon, andothers, forming the first community of believers and thus founding the KoreanCatholic Church together.

He struggled at times with issues such as ancestralrites, leaving and returning to the faith, but continued his witness until hiseventual arrest.

On April 8 (lunar February 26), he was executed bybeheading along with Jeong Yak-jong, Hong Nak-min, Hong Gyo-man, and threeothers.

His son and grandson were martyred in 1866, and hisgreat-grandson in 1871.

③ KwonIl-shin Francis (권일신 프란치스코)—One of the Three Pillars of the Founding Church

Kwon Il-shin was one of the three principalfounders of the early Church.

He converted and formed disciples such as Yi Jon-chang Ludovico (이존창루도비꼬) and YuHang-geom Augustine (유항검아우구스티노), spreading the Gospel widely in theChungcheong and Honam regions.

On his way to exile in Yesan, he died from injuriesinflicted in prison and was subjected to posthumous decapitation—a commonpunishment for those condemned as criminals against the state.

④ JeongYak-jong Augustine (정약종 아우구스티노)—Scholar, Catechist, Martyr, and Author of the Jugyo Yoj i (주교요지)

Jeong Yak-jong was a martyr and the first presidentof Myeongdohoe (명도회), one of the earliest lay evangelicalgroups.

He was the third of four brothers—Jeong Jae-won, Jeong Yak-hyeon, JeongYak-jeon, Jeong Yak-jong, and Jeong Yak-yong—and is now honored as a saint.

He was the father of St. Paul Chong Ha-sang (정하상바오로) and St. Columba Jeong Jeong-hye (정정혜콜룸바).

Recognizing the truth of Catholic doctrine, heconverted, deepened his study of the faith, and under the guidance of FatherZhou Wen-mo was appointed president of Myeongdohoe, where he inspired andinstructed many to the faith. His doctrinal knowledge was widely regarded asoutstanding among the Catholics of his time.

The Catechetical Text JugyoYoj i (주교요지, Jugyo Yoji)and Its Contribution to Early Evangelization

Jeong Yak-jong Augustine authored a two-volumecatechism titled Jugyo Yoj i (주교요지, Jugyo Yoji), which played a decisiverole in teaching the faith and spreading the Gospel in the early Korean Church.

The first volume explains foundational doctrines such as:

the existence of God,

reward and punishment after death,

the immortality of thesoul,

and includes apologetic arguments defending thefaith and refuting errors.

The second volume presents the doctrines of:

the Incarnation of the Son of God,

and the Redemption of humanity through Christ.

This catechism was written in simple and accessibleHangeul so that evenuneducated women and children could read and understand it.

Hwang Sa-yeong Alexius (황사영알렉시오) recorded inhis Baekseo (帛書, Silk Letter) that Jeong Yak-jong referenced various sources andadded his own insights while writing the text.

Father Zhou Wen-mo (주문모, Zhou Wenmo) formally approved the catechism, confirming that Jugyo Yoji wasnot merely a translationof Western texts but an original Korean synthesis of Catholic doctrine.

Jugyo Yoji circulatedas handwritten manuscripts for many years until it was printed inwoodblock form in 1864. Its contribution to the growth of the early KoreanChurch was immense. Its core teachings became what Korean Catholicstraditionally call the Four Great Doctrines.

The FourGreat Doctrines (4대 교리) of Korean Catholic Tradition

Incarnation and Redemption (강생구속)

The Son of God, Jesus Christ, became human and redeemed humanity by Hissuffering and death.

Anyone who believes and receives baptism can obtain salvation.

The Holy Trinity (삼위일체)

One God in three divine Persons—Father, Son, and Holy Spirit—distinct yetperfectly united in one divine nature.

This expresses the Christian truth that humanity receives salvation from theFather, through Christ, in the Holy Spirit.

The Existence of God (천주존재)

God exists as the Creator and ruler of the universe.

Reward for Good, Punishment for Evil (상선벌악)

God rewards those who do good and punishes those who commit evil.

Jeong Yak-jong remained steadfast in faith evenwhen his brothers and closest friends apostatized during the Shin-hae Persecution (1791).

He was condemned as a traitor and martyred bybeheading outside Seosomun (서소문,Seosomun) on February 26, 1801 (lunar calendar).

The early Korean Catholic lay association Myeongdohoe(명도회, Myeongdohoe) was foundedby the Chinese missionary Father Zhou Wenmo James shortlyafter his arrival in Korea. He appointed JeongYak-jong Augustine as its first leader. The purpose ofMyeongdohoe—literally “Society for the Enlightenment of the Way”—was to studyand teach Catholic doctrine.

Members of Myeongdohoe first dedicated themselvesto acquiring a deep understanding of Catholic teaching, and then encouraged oneanother to share the faith with fellow believers and with those outside theChurch. Father Zhou established clear regulations for the society, designatingmeeting places, appointing moderators, and requiring that men and women gatherseparately.

As the society spread across the country, itproduced remarkable results. Father Zhou himself drafted the strict MyeongdohoeRule, which governed its operations. Moderatorsappointed by him implemented a membership system that required candidates toreceive a monthly token of membership. Before joining, each person had todeclare their name and demonstrate singong—prayerand good works—and only those who practiced this faithfully were admitted.

According to HwangSa-yeong Alexius, a key member of the society, Myeongdohoe had sixofficial meeting places, known collectively as the “Six Assemblies.” Memberswould gather there on every major feast day to join the faithful in worship andto dedicate themselves to evangelization. Each assembly was composed of smallgroups of three to six members.

Hwang recorded that the group he led consisted ofsix members from the yangban and jungin classes,including Jo Sin-haeng. In the Baekseo (SilkLetter), Hwang wrote that both members and ordinary believers were so deeplymoved by the work of Myeongdohoe that “day by day, throughout the autumn andwinter of 1800, the number of new converts increased without ceasing.”

During the Shin-yuPersecution of 1801, Father Zhou Wenmo, President Jeong Yak-jong, andall principal leaders of Myeongdohoe were martyred, causing the society’sactivities to decline. However, letters from martyrs such as Yi Gyeong-eon showthat the organization continued to exist in some form afterward.

Today, groups bearing the names “Myeongdohoe” or“Myeongdowon” in various dioceses do not have a direct historical connection tothe original Myeongdohoe of the early Korean Church.