A major point that must be put a cross, one that I have used as a quick test to see if someone is closed minded or not is to ask a person if they believe there is a difference between fact and truth. The closed minded will argue against this.
I believe that truth is a person's own twist on a fact. For example, Fact - I have just drank a gingerbread late in Costa. My truth - It was a yummy drink. Some one else's truth - It was an overpriced cup of milky coffee . The most extreme version of this argument is fundamentalist extremism. What the extremists believe is correct is their reality, is not true for any one else who doesn't share that belief.
Now if truth is simply own own point of view on a fact, then truth is subjective. To go one step further, since the way we see the world is based on our own personal truths (extreme example again is fundamentalist extremists) then reality it's self is subjective.
We all walk around in our own little bubbles of reality, they can evolve as we do, or stagnate as we do. If you are starting down the road of magik what you will be doing is evolving your bubble. It was once said that 'Magik is the act of altering reality by sheer force of will'. This is you and how you perceive your reality bubble. If you believe hard enough, through whatever process, you can change your universe.