In math and engineering there is precision: there is a correct answer. If a bridge has to have a span of 100 yards there is no partial credit for building a span that is only 95 yards long. Ninety percent correct is not good enough.
Perhaps we can blame a lack of agreement and precision on Johannes Gutenberg who invented movable type which started the printing revolution. His was one of the greatest inventions of the last two thousand years. Movable type meant more books. More books meant more literacy. One might say that Gutenberg inadvertently caused the fragmentation of western Christianity that took place in the 1500's and the 1600's. In religion one was no longer dependent on an authority figure to tell you what was in the scripture. You could read scripture yourself which is exactly what people did. You could find out what scripture said and moreover you were not exclusively dependent on an authority to tell you what it meant.
But there is more going on than just Gutenberg. There are three factors that seemingly guarantee differences of opinion. They are physiology, background and desire.
We navigate the world in a body. It is with our senses that we perceive the world and we are all different. I told my students that it was always my ambition to play professional basketball for the Boston Celtics. Did they think that my being fat, old, short, slow and poorly coordinated had anything with my inability to do so? And the senses influence future perceptions, hence the old story about not being willing to even touch a cold stove having been burned on a hot stove.
Another factor is environment or personal history. We do not get to choose the country where we are born. We do not get to choose our parents. We do not get to choose the religious tradition that we are born into. Who knows the complete history of another person?
The third factor is desire. We have free will. From my early years, I wanted to be a teacher. I was a good student. I was rewarded for being a good student. Teaching was a profession approved of by society. Teaching answered my need to give service and it answered my needs for performance and approval. Teaching also allowed me to earn an adequate living for myself and my family.
Physiology, background and desire: is it any wonder why peop0le think and react differently? It might well be that it is remarkable not that we disagree but that we ever agree at all. But this diversity is not necessarily a bad thing.
I submit that life is like a musical performance. Each of us is an individual instrument. You are a trumpet. I am a drum and another person might be a violin or a piano. We can play solo performances of a given piece or we can make an interesting sound together. That we are not all the same makes us a kind of an orchestra. We might make a more interesting sound taken together and our differences are not so much differences as contributions.