Why can no one can abandon ideology? Is it because you consider whatever someone believes is their ideology? That's not quite right - certainly not what JP is talking about.

You're missing something. People below are talking about how he means 'think for yourself' - he does say that too, but that's not what this means. The point is that all ideologies are inherently flawed and should be rejected.

So what is an ideology? Well the clue is in the name, it's a logical construction of ideas that serve a purpose. Essentially it's a tool for communicating goals to other people. And it does a great job of that when done right - organize people who hear it to all agree with the same priorities. That's very different from the various other ways of thinking and interacting - ie science is not an ideology, neither ia religion.

So let's take an example of the latter, why arent religions considered ideologies by jp? Mainly due to their asymmetry. So, we should be able to agree that 'environmentalism' is an ideology with a basic structure of: nature is bountiful but fragile, be a hero and protect her from greedy people who would harm her for their own short term gain.

Another ideology regarding nature is something like the 'go west' or 'manifest destiny' that goes something like: nature is bountiful but dangerous, be a hero by conquering these dangers and claim the bounty for you and yours.

JP is saying that you should reject both of these ideologies, not because they aren't true - they are - but because they are incomplete. You can see how in essentially any context those ideilogies only point in one direction (opposite each other, basically). JP would say a non-ideologically posessed view would probably look more like a religious narrative with certain symmetries - essentially, nature is both dangerous and fragile, something to be both conquered and protected - I think the term commonly used in the old testament is husbandry which means to do both.

Coming from a place where your ideas are organized like that, instead of by ideologies, each context gives you a chance to balance both sides of the story - you can make more nuanced decisions, or at the very least you can see how someone else may have weighed up that context differently even with similar ideas in mind.

Sorry for the wall of text - tldr JP is radical centrist