Speaking of the decline in ritual, that reminds me of the very common view that, for its adherents, such-and-such ideology "is like their own religion." Communism, political correctness, the eco-friendly organic movement, etc. If it's just a short-hand for "they have their own rigid orthodoxy," then that's fine. But a lot of people push it seriously, as a send-up of the group's hypocrisy.
The most obvious lacking religious feature is the focus on the sacred supernatural. The subject matter is entirely profane, the causes and forces entirely secular.
Even leaving that aside, ideologies do not incorporate much ritual, which ideological people view as superstition.
They are particularly short on rituals that occur frequently, in a group setting, and that bond the members together. Please don't tell me that organizational meetings count -- during my activist days, I probably sat through hundreds of them, and they don't. They don't involve activities that put the members on the same wavelength, like dancing or marching to a common rhythm, chanting a prayer in unison, eating the same substance, or fixing their eyes on the same figure.
And of course your typical adherent of political correctness, etc., does not even attend meetings with fellow travelers. There is no communal behavior to reinforce and intensify their beliefs. They're just kind of cruising along through life, subscribing to some list of beliefs, aware that there are others with similar beliefs, but not meeting up regularly to solidify social bonds among themselves. Nothing like the weekly church gathering, periodic church dances, or even private daily prayers.
They've managed to get some of their idees fixes branded as national holidays -- but that doesn't mean they actually celebrate them. That was just a way to symbolically rub it in the face of those outside the ideology. What about the holidays that are not yet recognized by the government? They don't honor those either. "Festive" and "celebratory" are moods that you rarely or never find ideological people in, at least in a context related to their ideology.
It's no wonder that those who get into ideologies come off more as airheads, autistics, and killjoys.
Listing a handful of genuine examples of ideological rituals doesn't go against what I've argued. Sure, the national conventions of the Democrats and Republicans are intense group-bonding rituals, although those only happen every four years, not weekly or even yearly like the candlelight Christmas service. And sure, there are occasional purification rituals that the offenders of PC have to undergo before the mainstream of society will welcome them back. Perhaps at the beginning of their college career, they emptied their soul of "white guilt" before a group of their peers as a sign of good faith, to signal their intent to atone for their sins. And heaven forbid you violate the food taboo of drinking a Coke instead of an Oogave cola!
Still, these rituals are either very uncommon, or do not take place in group settings (like an individual's frequent observance of the food taboos against mainstream brands). By itself, that wouldn't hurt their status as a religion or not a religion, since rites of passage are also one-time-only affairs. But if the ideology doesn't involve frequent meetings that bond members together, these occasional rituals are not enough to give cohesiveness to the group, which any religion must have, no matter how large or small.
And none of this precludes an ideology from transforming into a religious movement. Fascism started out as just another ideology, but during the peak of Nazism in Germany, it did have a rather religious feeling to it. It's hard to say for sure because, again, the focus on the sacred supernatural is also a defining feature, and I'm not sure how much the broad membership looked to the movement with that concern in mind.
It seems part-way between militarism, which has all of the ritual stuff I've talked about but not necessarily any supernatural element, and a clear-cut religious movement. They had a lot of half-baked talk about mythology, but I wonder how much the average Nazi cared about that, compared to the intellectuals who discussed it more. Their invocation of various gods seemed more allusive than true-believer.