Contrary to popular belief, Aglipay did not join the IFI until one month from its proclamation by de los Reyes and the Unión Obrera Democrática.

Born in Batac, Ilocos Norte on May 5 and baptized on May 9, 1860 in the Roman Catholic Church, Aglipay personally preferred May 8 as the celebration for his date of birth.

[1] He was the third child of Pedro Aglipay y Cruz and Victoriana Labayán y Hilario and became an orphan at a young age who grew up in the care of relatives at the tobacco fields in the last volatile decades of the Spanish occupation in the Philippines.

Arrested at age fourteen for failing to meet his quota as a tobacco-picking worker for a Spanish tobacco grower, he later moved to the country's capital of Manila in 1876 to study law under the tutelage of lawyer and private school owner Julian Carpio, with the financial help of his uncle Francisco del Amor Romas who was a menial employee of the Dominican Sisters School of Santa Catalina.

During his time in Santo Tomas, Aglipay met José Rizal, a senior medical student who used to be his fencing partner, and a newly-transferred Isabelo de los Reyes who also came from Letran.

He then discontinued his law and theology studies at Santo Tomas and entered the Roman Catholic seminary in Vigan, Ilocos Sur in 1883 at age 23, as previously influenced by Rizal.

Aglipay then began a career as an assistant priest to Spanish friars in various parishes around the main northern island of Luzon, notably in the Roman Catholic Archdiocese of Nueva Segovia.

[8] He later dropped Cruz in his surname and while serving in Victoria, Tarlac, Aglipay discreetly gave aid to the revolutionaries and employed thirty carpenters who in reality were revolutionists in touch with the Katipunan group.

Aglipay then organized the said revolutionists and called their group Liwanag ("Light"), a local auxiliary of the Katipunan based in Victoria, Tarlac.

With Roman Catholicism as the state religion, Manila Archbishop Bernardino Nozaleda tasked Aglipay to confront the revolutionary leaders, offering them a level of autonomy in the future for the Philippines if they would end the rebellion.

The fighting that broke out between the U.S. and Filipino forces on February 4, 1899, prompted Aglipay to withdraw to Ilocos Norte to organize an armed resistance and was given the rank of lieutenant-general.

[15] Following the end of the war in 1902, writer-activist Isabelo de los Reyes was working towards the formation of a nationalist church that is independent of Rome.

On August 3, de los Reyes and his labor group Unión Obrera Democrática proclaimed the establishment of the church and suggested in absentia that Aglipay be its first head bishop.

[5] According to renowned historian Teodoro Agoncillo, Aglipay finally decided to join the new church after his talks with Francisco Foradada, a Spaniard Jesuit priest and author, backfired.

In a meeting held at the Jesuit House in Santa Ana, Manila, Aglipay was allegedly offered to be appointed bishop or archbishop with a large sum of money thrown in if he would return.

He even met with American Protestant leaders and tried to persuade them to assist and join them in their new Filipinized church in order "to divide the ranks of the [Roman] Catholics."

In a final attempt, the Jesuits tried to negotiate again with Aglipay years after he joined the new church and accepted the supreme bishop post through a more diplomatic Spanish Father Joaquin Villalonga.