Everyone's perception on the world is different. When you see something happen, your brain automatically and often unconsciously makes decisions based on it. Everything that makes up your perception on the world is based on what you decide they are.
Since people's perceptions are different, we can't truly understand each other's world. In attempt to understand each other, we bind things and share perception through the use of language.
The fact is, if you decide that something is different from what everyone else decides it is, you are seen as being delusional or weird, but in actuality your perception is just a bit different.
See my sig.
It's only ________ if you decide it is.
You can put virtually anything into that blank.
It's only a problem if you decide it is.
It's only impossible if you decide it is.
It's only real if you decide it is.
It's only a hallucination if you decide it is.
It's only a lie if you decide it is.
It's only the truth if you decide it is.
It's only a car if you decide it is.
It's only a box if you decide it is.
These decisions are what make people different. Even if it doesn't make sense to you, it does to them, because they decided differently. And you never have to change your perspective, yourself, just to fit the world of someone else a little bit better.
Imagine this.
Your teacher draws a shape on the chalkboard. It looks like this: O
He asks the class what it is.
The majority say it's a circle.
Some say it's a ring, a ball, the letter "O".
Someone might say it's a hole in the side of the chalkboard.
But you, YOU say it's a triangle. You decided it was a triangle, you believe it is a triangle, your perspective of it has been a triangle all your life.
And you absolutely refuse to believe that it is anything else.
No one can do anything about it. Your perspective of the world is different, everyone thinks you're crazy, but you don't care.
A similar thing happens with colour blindness. If they are red-green colour blind, they still see green, but what they see as green is different with what you see as green. You call it the same thing, you see it as the same thing, but it is different, and there's nothing you can do about it.
Religion is just a lot of people who's perspective on the world is that God exists. They decided God exists, they believe that God exists, and of course, they refuse to believe otherwise. Atheists decided that God doesn't exist, they believe that God doesn't exist, and refuse to believe otherwise. The perspectives are fundamentally different, so of cours there is conflict and lack of understanding.
Nobody is the same. Everyone sees the world differently. But you can decide that's not true if you choose to do so.