The other day someone asked whether or not the works of Homer were really "secular" literature. The attempt to classify Homer as secular or religious vexes me greatly, because in my opinion, Homer predates "religion" or "secularity." But especially religion. "Religion" is something that happens when you divorce spiritual and behavioural practices from culture and peoplehood, done most famously by Christianity and Islam for the purposes of marketing themselves far and wide.
The way Greek people reacted and bonded to Homer was really not a simple activity like "believing in" something. It's more that they saw in the text a powerful and beautiful reflection of themselves, and desired to grow into the text and for the text to grow into them. Jews have a similar relationship to sacred literature. It's not about "belief in," it's about a long and deep relationship with the words and the people behind them.
And it's not just about how people react to holy stories or perceived commands--the difference is much greater than that. I'm doing a lot of reading on alchemy in my spare time, and one of the interesting points that emerges is that some of the wackier alchemical shit was less bizarre for people in ancient Babylon and Egypt, because their ordinary metallurgy was intensely bound up in spiritual practices already, for example the positions of the stars and what relationship each star was supposed to have with what material lying on the anvil, and what power/personality was thought to be in relationship to that star. Contrast that with how Islam for example struggles with separating "real religion" from "culture" and "superstition" or how Christianity historically glommed onto any available culture and assimilates it because in the end, culture doesn't matter much, except as a tool to get more people to accept Jesus.
Jewish holy texts and oral tradition have no word for "religion" and no nice shorthand to describe someone as "religious." There is not even a word for "Judaism." Instead, you talk about the people and what they do and what they ought to be doing. Although my knowledge of this is superficial, it sounds to me much more similar to how Elders of some First Nations I've heard describe themselves, where the word for your people is "the people" and your so-called religion is what the people do. If a classical Jewish text wishes to describe someone as being spiritually praiseworthy, what people often call today "religious," it has to make a nice long list of their behaviours, such as with Rabban Yohanan ben Zakai in Masekheth Sukah:
He never engaged in smalltalk,
nor did he ever walk four armlengths without studying Torah,
or four armlengths without tefilin,
nor did anyone ever get to the study hall before him,
nor did he ever sleep or doze in the study hall,
nor did he think Torah thoughts in filthy alleys,
nor did he ever leave anyone behind in the study hall.
Nobody ever saw him sitting silently, but rather always sitting and studying out loud,
and no one ever opened a door for his students; he did it himself.
He never said anything that he had not heard from his teacher,
and he never said, “It is time to stop studying” except on the eve of Pesah and the eve of Yom Kipur.
Today of course we have to put up with using words like "Judaism" and even describe it as a "religion" because that is the only way of conveying to some people that what you're doing is important and you don't feel like explaining it to them. To me even communicating in this way is a concession to a world colonised by Christianity, so still in place of explaining something as "It's my religion," I think it's better and more accurate to say more like this is my people, this is what we do as part of our agreement with God or for whatever other reason.
Honestly, I'm a yeshiva student (and Chief Graffiti Inspector, and secretary) studying with an Orthodox rabbi for semikhah ("ordination," kinda... same problem) and I have about as much in common spiritually with some Christian as with a complete atheist.