Several questions to try to answer here - probably because of the way I think (have developed)
Firstly - suffering emotional pain. It's about recovery to me, a mix of the danger of falling into self-pity, dwelling on emptiness following disappointment and being too ready to blame the entity for inflicting the pain. Well, yes, the person causing it may be to blame if in all honesty we did nothing to provoke it (including our demands of people/situations) but we have to blame ourselves if we make our recovery difficult.

As for beliefs - I've never been put under threat of punishment/sanction for my beliefs though a few have raised their brows when I speak of certain aspects. There are people of certain faiths whose Holy Book demands its followers expunge non believers but I've met a few following that faith who happily live alongside us non-followers as long as we don't deride their beliefs and customs...fine by me. We all believe what we've come to see as our model of creation, definition of soul, etc.

I think the best way to "understand" people (a weird way to describe it - I'd be happier with the word "appreciate") is to let them be themselves by touching as lightly as possible on their individuality. I believe that every interaction with others beyond simple transactions, broadens our insight into people generally (i.e. beyond just the individual encountered) but I'm always mindful that my "understanding" of people is a reflection of my personal experiences of people and life. Shrinks have tried to standardise this for ages with little success. And...it isn't always easy just to allow others' individuality just to flourish if there's some kind of threat or confidence trick in their approach. But even that is about seeing the signs; our accumulated experiences.

An interesting question but....understanding? I doubt one could ever understand another completely. We'd need them to trace their paths exactly with us hand in hand - and that's going to colour how they react to us, even if they're aware enough of how their paths developed. No one could understand me though they may recognise events and features that have contributed to where I am, my attitude, etc. I don't expect them to. I reckon I'm predictable and that seems to be enough for most people I meet.