1. What makes us different from others are exactly the opinions based on perspectives, not the universal truths. I actually find it hard to think of many universal truths that could define us.
2. Opinions based on perspectives could be actually true. E.g. if God exists, than the Pope was right, but that doesn't change the fact that he didn't really know the truth, he just believed, he had an opinion.
Other times, there is simply no truth and it's all about the perspective. E.g. Is the death penalty good?
What I'm trying to say is that our personal truths define our set of values and ultimately our way of living.
We have established that these truths have an emotional and rational part (one or both of them), so they could be changed by:
A. Facts - over time, reality simply proves us we were wrong.
B. People - stronger arguments or a fine ability to manipulate our feelings.
C. Time - long periods of time simply alter our point of view.
In many cases, our opinions are shattered because their strength is proved to be an illusion. We rush into believing that we know the truth, but suddenly facts or other arguments kill all of these instantly.
But what about when:
A. Facts simply cannot prove or disprove our beliefs. E.g. A believer defines God as something that's in all of us and at the same time out of this Universe. Reality simply cannot provide any facts to disprove it.
B. Sometimes the arsenal of "arguments" reaches its limits and capacities. If there are cases when reality cannot disprove one thing, then rational arguments have even smaller chances to succeed. E.g. To stick with religion, I think that all of the possible anti-religious arguments have been said already, and some people have already heard them all, but they simply resisted.
Regarding the manipulation of feelings, I think this has an absolutely huge potential, but only before arguments or reality come into play. I truly believe that the way arguments are exposed is important, but unless some kind of hypnosis is induced, cases in which even universal truths like 1+1=2 could be attacked, only the talent for narrating doesn't have the power to change very rooted beliefs.
C. The time matter is very tricky for me. On one hand, I think that time itself without other elements has nothing to do with beliefs. At the same time, time itself brings with it changes. So can some of our strongest beliefs remain constant throughout eternity?