Many of my favorite films involve themes about social issues, social change, and social activism. Here's a list, in alphabetical order. Be aware that I like some more than others, but all are certainly worth seeing.
The Battleship Potemkin
The Bicycle Thief (1948)
Breaking Away (1979)
Chariots of Fire (1981)
The Cider House Rules (1999)
City Lights (1931)
The Conversation (1974)
Guess Who's Coming to Dinner (1967)
Ghandi (1982)
Best scene: Actually, the most disturbing scene: the Jallianwalla Bagh massacre in Amritsar on 13 April 1919, in which British troops opened fire on a peaceful gathering of protesters, killing 379 and wounding 1200. The next best scene, equally powerful: when confronted by a grief-stricken Hindu begging Gandhi for forgiveness after he killed a Muslim child, Gandhi tells the man to adopt a young Muslim orphan … and raise him as a Muslim.
In the Name of the Father (1993)
Best scene: After Guiseppe dies, the prisoners light paper on fire and drop it from their windows in protest and remembrance.
The Last Picture Show (1971)
Lone Star (1996)
Midnight Cowboy (1969)
Mississippi Burning
Network
Paths of Glory
Salvador (1986)