Some of the early 20th century Jewish socialists who immigrated to the United States were ideologically atheists.
They might have eaten pork on Yom Kippur, but they derived intense pleasure from doing so.
They counted their money in Yiddish and sometimes enjoyed listening to a chazzan.
Their grandsons, however, are no longer Yankel or Berel.
They watch baseball on Yom Kippur and often do not even know that the day is Yom Kippur.
For them, it is just a date somewhere in September or October.
The old-timer worked hard to obliterate his Jewishness; his sons and daughters and his grandchildren don't have any need to do so.
–Rabbi Adin Steinsaltz
From an essay, “Happy (17th of Tevet) New Year,” by Rabbi Adin Steinsaltz