Ali Shariati's thought, in my view, is liberation theology, very much influenced by Marxism of the era of anti-colonial struggles, especially Frantz Fanon's ideas. He was a lay man and very anti-clerical, teaching the masses a history of popular revolts "against foreign domination, internal deceit, the power of the feudal lords and wealthy capitalists" (Ali Shariati, "Red Shi'ism (the Religion of Martyrdom) vs. Black Shi'ism (the Religion of Mourning)"). He was immensely popular, one of the chief influences on young revolutionaries of the Iranian Revolution, which, not so coincidentally, was one of the last great anti-neo-colonial revolutions in the sixties and seventies, happening exactly at the same time as the Sandinista Revolution.
Ervand Abrahamian says that, after Shariati's untimely death (which many think was the work of SAVAK), Shariati's favorable interpretations of Marx and Marxist thought were expurgated from his texts that were published in Iran, whereas his criticisms of Marxism were left intact in them, thus giving Iranian masses a wrong impression of what Shariati really thought (see Iran Between Two Revolutions, Princeton University Press, 1982).
And yet, his thought still lives on among Iranians, no doubt.
What would Shariati say to the ruling clerics of Iran were he alive today? "Shi'ism left the great mosque of the common people to become a next-door neighbor to the Palace of 'Ali Qapu in the Royal Mosque" ("Red Shi'ism (the Religion of Martyrdom) vs. Black Shi'ism (the Religion of Mourning)").