https://en.wikipedia.org/wiki/Felix_Adler_(professor)

While in Germany, he was strongly influenced by neo-Kantianism, especially the notions that one cannot prove or disprove the existence of a deity or immortality, and that morality can be established independently of theology.

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Adler introduced his concept of Judaism as a universal religion of morality for all of humankind. The sermon was his first and last at Temple Emanu-El.

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On May 15, 1876 he reiterated the need for a religion, without the trappings of ritual or creed, that united all of humankind in moral social action.[7] To do away with theology and to unite theists, atheists, agnostics and deists, all in the same religious cause, was a revolutionary idea at the time.

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Adler talked about "deed, not creed"; his belief was that good works were the basis of ethical culture.