How do Jews feel about assimilation? The answer is “it depends.” Gerson Cohen argued that it is a matter of being realistic and that assimilation is a blessing: “Scripture spoke in the language of the world, and the Rabbis spoke in the language of their world.”
However, he recognizes that “there have always been opportunists and despondent people who have preferred to identify totally with the majority and have slipped away from the Jewish community.”
With this phenomenon, Cohen says, nothing can be done. Fear might be the leading cause of this “disappearance.” However, he pleads not to see assimilation in merely negative terms and states: “First, we Jews have always been, and will doubtless continue to be, a minority group; and second, that a minority that does not wish to become fossilized, will inevitably have to acculturate itself - to assimilate - at least to some extent.”
Diaspora will continue, and assimilation will continue to be needed. He states: “You will recognize that some of the effects of assimilation will often sadden us all, but you will also be aware that the phenomenon of assimilation also presents us with unprecedented opportunities to reinterpret the Jewish tradition so that it will be relevant to the needs of the twentieth century.” Hence, his term “blessing.”
https://www.jewishhistory.fm/wp-content/uploads/2018/10/Gerson-Cohen-Blessings-of-Assimilation.pdf