In the early 19th century, Pelaez advocated for the secularization of Filipino priests and is considered the "Godfather of the Philippine Revolution."

[5] Although Pelaez decided to become a secular priest, he maintained close ties with the Dominicans his whole life.

Along with Father Mariano Gomez, Pelaez started organizing activities calling for the return of control of Philippine parishes to Filipino seculars.

[5] Seeking to have the royal decree cancelled or changed, Peláez published anonymously a long formal protest titled "El Clero Filipino" (The Filipino Clergy) in a Spanish newspaper, El Clamor Público, in 1850.

Together with Francisco Gaínza, Peláez founded El Católico Filipino, the first Catholic newspaper in the Philippines.

[6] With his knowledge of canon law, Peláez wrote against this policy; nor did he hesitate to criticize the clergy both secular and regular priests, Spanish or Filipinos when appropriate.