> However I'm now in situations where the world is divided and asking questions (in order to make my own mind up) is considered some kind of admission of guilt for being part of the "other". For example: Asking someone why they think immigration is good/bad. If it's a belief they hold, I'm interested in knowing the thought process and making my own conclusions based on something I might not have known. But the act of asking the question makes the person, who may not have put too much original thinking in; quite defensive.

It may be a matter of knowing when to stop. My personal experience is that most people will try to answer even sensitive questions when you approach them with genuine interest and make some effort to formulate questions in a way that doesn't imply some sort of value judgement. If this is difficult, just be explicit and explicitly say you're not trying to judge or offend them.

Sure enough, you'll hear people make an argument that you find unconvincing, or they may not answer the exact question that you asked, and some people will even admit they don't know why they believe something. When that happens, you'll have to accept that as their answer (and draw your own conclusions in silence).

People do get hostile when you keep "nagging" - asking more and more questions - when it's clear that they aren't interested in the subject or haven't thought about it much. To the other person it feels like you're either trying to make them feel stupid or change their mind. And you're getting none the wiser anyway because those who do not get offended will just make up their "reasons" on the spot.

Obviously avoid the mistake to ask someone for their opinion, and then immediately returning the "favor" by giving your opinion on the matter.