Ideas have consequences. Says Paul Tillich in 1967:

The anti-religious attitude of almost half of present-day mankind is rooted in this seemingly professiorial struggle between Hegel, Feuerbach, and Marx, with both of the latter coming from Hegel. Feuerbach turned Hegel upside down, and then Marx introduced the sociological element. The projection of the transcendent world is the projection of the disinherited in this world. This was such a powerful argument that it convinced the masses of people. It took more than one hundred years before the labor movements in Europe were able to overcome this Feuerbachian-Marxian argument against Hegel’s attempt to unite Christianity and the modern mind.

–Paul Tillich, Perspectives on 19th and 20th Century Protestant Theology (New York: Harper & Row, 1967), 141.

Thus Tillich traces the line of the “left-wing” Hegelians, who turned Hegel’s Absolute Spirit into absolute materialistic class struggle.