Isabelo de los Reyes y Florentino, also known as Don Belong (July 7, 1864 – October 10, 1938), was a prominent Filipino patriot, politician, writer, journalist, and labor activist in the 19th and 20th centuries. He was the original founder and proclaimer of the Iglesia Filipina Independiente, the first-ever Filipino independent Christian Church in history in the form of a nationalist church, which was proclaimed in 1902. He was also the founder and first president of the first-ever labor union federation in the Philippines, the Unión Obrera Democrática. He is popularly known today as the "Father of Philippine Folklore", the "Father of the Philippine Labor Movement", and the "Father of Filipino Socialism". His mother, who was of mixed Spanish and Filipino descent and forced in marriage at the age of 14, is recognized as the first significant female poet of the Philippines for her works in both Spanish and Ilocano and is recognized as the "mother of Philippine women's literature" and a pioneer in Philippine lesbian literature. De los Reyes may have been distantly related to Ventura de los Reyes, a creole merchant who was the first Philippine delegate to the Spanish Cortes through his father's side. He may also have been a "distant cousin" of José Rizal through a Chinese tax collector married to both Rizal's grandmother and de los Reyes' grand-aunt.

In 1880 at age 16, de los Reyes went to Manila without his uncle's consent,

Ever since he was young, de los Reyes had been intrigued by the growing interest in the "new science" of El saber popular (folklore). On March 25, 1884, Jose Felipe Del Pan wrote an article in La Oceania Filipina calling readers to contribute folklore articles, inspired by interest in the subject in the peninsula. De los Reyes was urged by del Pan to contribute and gave him books on the subject that piqued his interest. Two months later, de los Reyes submitted his articles concerning the folklore of Ilocos, Malabon, and Zambales. De los Reyes declared that he founded El Ilocano to "serve [our] beloved pueblo Ilocos by contributing to the enlightenment of her children, defending her interests." El Iloco lasted for seven years. He began reading the works of Pierre-Joseph Proudhon, Mikhail Bakunin, and other socialist thinkers. He also joined protest actions and was imprisoned for a short time by police authorities. He was released and was forced to relocate from Barcelona to Madrid. The Union Democratica de Litografos, Impresores, Encuadernadores y Otros Obreros was thus formed, which came to be known as the labor union federation Union Obrera Democratica (UOD) on February 2, 1902. De los Reyes was its first president.</blockquote>

On his return to the Philippines in 1901, de los Reyes campaigned for the establishment of a Filipino Church independent from the authority of the Roman Catholic Church. On August 3, 1902, with the help of Pascual H. Poblete and other members of the UOD, the Iglesia Filipina Independiente (Philippine Independent Church or also known as the Aglipayan Church) was formed, with Gregorio Aglipay, an excommunicated priest from the Roman Catholic Church, as its proposed head (albeit in absentia). His wife died of illness in 1897 while he was in Bilibid prison.

De los Reyes' last marriage in 1912 was to the 18-year-old María Lim, a mestiza de sangley from Tondo. They married in the independent Aglipayan Church. They also had several children before María also died in childbirth in 1923. Before her death, she had asked that they be married according to the Roman Catholic rite, to which de los Reyes agreed.

With his own family spanning Roman Catholic and Aglipayan traditions, de los Reyes was tolerant of religious diversity among his children. His namesake Isabelo de los Reyes Jr. (1900–1971), a son from his second marriage with Lopez and whom he shares the same death day with at October 10, although baptized Roman Catholic, was ordained an Aglipayan priest and later became Obispo Máximo IV of the Church for 25 years. De los Reyes Jr. is also widely known as the "Father of Ecumenism in the Philippines". His daughters Ángeles, Elisa, and Elvira also from his second marriage, along with Crescencia from his third marriage, became professed nuns in the Roman Catholic Church.

Publications

  • El Ilocano
  • La Lectura Popular
  • El Municipio Filipino
  • Filipinas ante Europa
  • El Defensor de Filipinas
  • La Redencion del Obrero
  • Boletin de la Iglesia Filipina Independiente
  • La Iglesia Filipina Independiente: Revista Catolica

Scholarly works and essays

thumb|[[Bust (sculpture)|Bust of de los Reyes situated at the University of the Philippines School of Labor and Industrial Relations in UP Diliman.]]

  • El Folk-lore Filipino
  • La expedicion de Li-Ma-Hong contra Filipinas
  • Ilocandias
  • Articulos Varios
  • Las Islas Visayas en la epoca de la conquista
  • Historia de Filipinas
  • Historia de Ilocos
  • Memoria sobre la revolution
  • Memoria de agravios de los Filipinos
  • Kalendariong Maanghang
  • La Religion Antigua de Filipinas

Novels and stories

  • Mariquit the Tramp
  • Sing sing ni Diego
  • Ang Singsing ng Dalagang Marmol (circa 1905), a novel

Religious texts

  • Gregorio Aglipay y otros prelados de la Iglesia Filipina Independiente
  • Biblia Filipina
  • Oficio Divino
  • Catequesis
  • Plegarias
  • Genesis Cientifico y Moderno
  • Calendario Aglipayano

He also translated into Iloko the Gospels of the New Testament and the Acts of the Apostles.