Outside of a Jewish context, all Jewish holidays appear to be "religious holidays" but that is not actually the case. Judaism is old enough that it is simultaneously a religion, a system of ethics, a social ideology, and a trans-national quasi-citizenship. (To be a Jew is, first, to claim ancestral citizenship – by birth or "naturalization," i.e., conversion – in the ancient tribal nations of Israel and Judah.) That is why, within Judaism, there are religious holidays, like Passover and Yom Kippur, which require abstinence from work, school, etc., and may also require fasting; and there are secular holidays, like Hanukkah and Purim which, while they may have a religious aspect or component, are festive occasions that generally reside on the secular side of Jewish history and tradition.