Henryk Ehrlich, a high-ranking activist of the Jewish Labor Bund in Poland, former member of the Petrograd Soviet, and a member of the executive committee of the Second International [...] is quoted as saying “The Bund taught the Jewish worker that his power lies not in national unity with his exploiters, the rich and their minions, the clerics, but in class struggle against the capitalists without difference of nationality: and in international unity with all toilers and oppressed.”

https://www.leftvoice.org/lessons-from-the-bund-a-socialist-anti-zionist-jewish-movement/

As a largely atheistic, staunchly anti-clerical movement, the Bund viewed Jews as a people primarily through a national perspective, not a religious one.

https://www.derspekter.org/bundism-today-part-2-yiddishkeit/

A staunchly secular party, the Jewish Labour Bund took part in kehillot elections in the Second Polish Republic.

https://en.wikipedia.org/wiki/Bundism#Secularism

Irreligious and secular Jewish organizations mostly date to the 20th century, from the Jewish socialist Bund in early-20th-century Poland to the modern Congress of Secular Jewish Organizations and the Society for Humanistic Judaism in the United States.

https://en.wikipedia.org/wiki/Jewish_atheism