A prominent member of the Social Democratic Party of Germany (SPD), he has been both condemned and praised as a "revisionist" who challenged major aspects of Karl Marx's thought.

After World War I, during which he joined the anti-war Independent Social Democratic Party of Germany (USPD), he was again a member of the Reichstag from 1920 to 1928.

Bernstein was born in Berlin-Kreuzberg to Jewish parents who were active in the Reform Temple on the Johannistrasse whose services were performed on Sunday.

Consequently, Bernstein, together with August Bebel and Wilhelm Liebknecht, prepared the Einigungsparteitag ("Unification Party Congress") with the Lassalleans in Gotha in 1875.

Bernstein later noted that it was Liebknecht, considered by many to be the strongest Marxist advocate within the Eisenacher faction, who proposed the inclusion of many of the ideas that so thoroughly irritated Marx.

However, two assassination attempts on Kaiser Wilhelm I the next year provided Chancellor Otto von Bismarck a pretext to introduce a law banning all socialist organizations, assemblies and publications.

There had been no Social Democratic involvement in either assassination attempt, but the popular reaction against "enemies of the Reich" induced a compliant Reichstag to approve Bismarck's Anti-Socialist Laws.

[3] Shortly before the Anti-Socialist Laws came into effect, Bernstein went into exile in Zurich, accepting a position as the private secretary of Karl Höchberg, a wealthy supporter of social democracy.

In 1888, Bismarck convinced the Swiss government to expel a number of important members of German social democracy and so Bernstein relocated to London, where he associated with Friedrich Engels and Karl Kautsky.

Back in Zurich, Bernstein became increasingly active in working for Der Sozialdemokrat (Social Democrat) and later succeeded Georg von Vollmar as the paper's editor, which he was for 10 years.

He also communicated with various English socialist organizations, notably the Fabian Society and Henry Mayers Hyndman's Social Democratic Federation.

On 1 April 1895, four months before his death, Engels wrote to Kautsky: I was amazed to see today in the Vorwärts an excerpt from my 'Introduction' that had been printed without my knowledge and tricked out in such a way as to present me as a peace-loving proponent of legality quand même (at all costs).

On 4 March 1920, as an expert on Anglo-German relations under the German Empire, he became a member of the parliamentary committee investigating the war guilt question.

He was one of only a few deputies on the committee to admit Germany's responsibility for the outbreak of war, setting himself apart from the majority of Reichstag members in the bourgeois parties.

Bernstein indicated simple facts, which he considered to be evidence that Marx's predictions were not being borne out while he noted that while the centralization of capitalist industry was significant, it was not becoming wholescale and that the ownership of capital was becoming more and not less diffuse.

[further explanation needed][11] Looking especially at the rapid growth in Germany, Bernstein argued that middle-sized firms would flourish, the size and power of the middle class would grow and that capitalism would successfully adjust and not collapse.

Therefore, he rejected revolution and instead insisted the best strategy to be patiently building up a durable social movement working for continuous nonviolent incremental change.

[19][20] Bernstein considered protectionism (high tariffs on imports) as helping only a selective few, being fortschrittsfeindlich (anti-progressive) for its negative effects on the masses.

In contrast, he argued that free trade led to peace, democracy, prosperity and the highest material and moral well-being of all humanity.

Bernstein was sympathetic to the idea of imperial expansions as a positive and civilizing mission, which resulted in a bitter series of polemics with the anti-imperialist Ernest Belfort Bax.

He never identified as a Zionist, but after initially favouring a wholly assimilationist solution to "the Jewish Question", his attitude toward Zionism became considerably more sympathetic after World War I.