If you earnestly wished to "see the point", you're tripping yourself with by taking for granted "what it means to everyone else.." and things like "living in idea space"
There are traditions of study/thought that use ideology the way you mean, and traditions that don't. The variety of use is well-represented and has been since the word came into use. Likewise, "idea space" is a specific concept that some people accept as sensible and others don't. Again, the variety of relationships to it is well-represented (and stretches back millennia, on that one).
You can actually see an example of this kind of differing-perspectives-in-wide-use in the way use used "the moral basis of Christianity but not the religion itself" in your own comment above. While Platonic ideas predate Christianity and have much influence on its shape and study in the West, the that statement would strike most traditional and many modern Christian thinkers as non-sensical. To them, there is no sensible separation of Christianity's "moral basis" from its Church/people and trying to make some distinction is as alien and "pointless" to them as different senses of ideology are to you.
And yet, of course it's interesting to think about Christianity's "moral basis" as an ideology existing in "idea space" because it lets you relate that part of Christianity to other things that you feel are comparable using techniques that you know how to work with and have confidence in. That's pretty much exactly what's going on with social scientists/philosophers who think about ideology in the way I've been describing above.
If you earnestly wished to "see the point", you're tripping yourself with by taking for granted "what it means to everyone else.." and things like "living in idea space"
There are traditions of study/thought that use ideology the way you mean, and traditions that don't. The variety of use is well-represented and has been since the word came into use. Likewise, "idea space" is a specific concept that some people accept as sensible and others don't. Again, the variety of relationships to it is well-represented (and stretches back millennia, on that one).
You can actually see an example of this kind of differing-perspectives-in-wide-use in the way use used "the moral basis of Christianity but not the religion itself" in your own comment above. While Platonic ideas predate Christianity and have much influence on its shape and study in the West, the that statement would strike most traditional and many modern Christian thinkers as non-sensical. To them, there is no sensible separation of Christianity's "moral basis" from its Church/people and trying to make some distinction is as alien and "pointless" to them as different senses of ideology are to you.
And yet, of course it's interesting to think about Christianity's "moral basis" as an ideology existing in "idea space" because it lets you relate that part of Christianity to other things that you feel are comparable using techniques that you know how to work with and have confidence in. That's pretty much exactly what's going on with social scientists/philosophers who think about ideology in the way I've been describing above.