During the Occupation of Bajor, he was a teacher in the Singha refugee camp and kept the faith alive for a great many Bajorans there. Among his students was a young Kira Nerys. During the closing days of the Occupation, however, Fala secretly lost his faith in the Prophets and instead became a follower of the Pah-wraiths. He joined the cult that worshiped them soon after while maintaining his vedek status in public.
In 2375, he met Dukat, who had recently believed he was the Emissary of the Pah-wraiths. Dukat convinced Fala he was a new man and wanted to follow the path of the Pah-wraiths. Fala forgave Dukat's actions during the Occupation and believed he was walking the path of the Prophets then and therefore not fully responsible. He helped Dukat establish a community on the abandoned station Empok Nor for the Cult.
Later in 2375, he helped to kidnap Colonel Kira Nerys in order to convince her of his newfound faith. He traveled to Deep Space 9 and met with her, giving her a homing transponder. He soon went there to explain himself and escorted her around to let her talk to the members, who were following the old ways including taking a vow of abstinence. He tried to convince her that the Prophets had abandoned their people. He wanted Kira to join the Cult, assuring her that Dukat was a changed man, but Kira would not hear of it. When the child of Mika and Benyan was born and found to be half-Cardassian, Fala accepted Dukat's explanation that it was a symbol of their covenant from the Pah-wraiths. Kira challenged him later, but he responded that she just can't accept the possibility it might be true.
When Dukat planned a ceremony where the community would kill themselves to be with the Pah-wraiths, Fala accepted it along with the rest. However, Kira exposed his plan by mixing up the pills they were to take. Fala brought Dukat another tablet, but it was clearly not his and he tried to get out of it. Soon, it was clear even to Fala that Dukat wasn't what they thought. While the rest of the Bajorans turned on Dukat, however, Fala still carried out his own suicide, only responding with "faith" when Kira asked him why. She would later wonder if he meant he never lost his faith, or if he felt betrayed by it. (DS9: "Covenant")