the PLO in general and Fatah in particular never were theoretically driven movements guided by strict ideological tenets. Instead, as Yezid Sayigh notes, they tended to a simple nationalism that lacked ideological depth with violence constituting the main source of political legitimacy and national identity. With a focus on practice without substantial theoretical underpinnings, what divided the different secular factions in the 1960s and 1970s were questions not so much of what ideology should prevail after liberation, but instead of how to liberate Palestine, who was to liberate Palestine, and how much of it. Thus, as the PLO and its factions became practical fronts to wage armed resistance against the Israeli occupation… they incorporated a number of members who did not necessarily adhere to its secularist postulations.

[…] little suggests that the [political] prisoners who belonged to the secular factions were particularly sensitive to their more religious coprisoners, and [ex-Fatah Hamas leader Muhammad] Abu Tayr writes that “in my room were ʿUmar al-Qasim, a member of the political bureau of DFLP, and ʿAbd al-Latif al-Ghayth, a leader of PFLP in Jerusalem, and they sarcastically mocked anything connected to religion.”

As a number of militants such as Abu Husayra and [Ahmad] Muhanna began reading Islamic literature in prison, it appears this endeavor was in fact a direct response to the attacks and mocking by the Marxist revolutionaries in PFLP and DFLP.

— History of Palestinian Islamic Jihad by Erik Skare (Page 72 - 73)