Judaism, Christianity, Environmentalism
As I have often noted, the most dynamic and influential religion of the past hundred years has not been Christianity, let alone Judaism, the two religions that created the Western world. Nor has it been Islam. It has been Leftism.
Leftism has influenced the literary, academic, media, and, therefore, the political elite far more than any other religion. It has taken over Western schools from elementary through graduate.
For most of that time, various incarnations of Marxism have been the dominant expressions — and motivators — of Leftism: specifically, income redistribution, material equality and socialism. They are still powerful aspects of the left, but with the downfall of most communist regimes, other left-wing expressions have generated even more passion: first feminism and then environmentalism.