Each spiritual teaching holds it's truth, the truth realized by the founder, but we as practitioners see only the truth we our self realizing through practicing the teaching we chose to learn and understand, as long we are practicing we can not see or understand the teaching on a higher wisdom level. But only up to the level we our self has realized.
1: So why do we keep telling others they are wrong? Does our own understanding become the only right because we believe in that teaching?
2: Should we not be more focused on our own path? And not about what others follow or believe in?
3: can it be that what others belive or say holds a deeper understanding of truth than what we ourself do, so we can not see higher truth yet? And therefor not understand those who have realized more then ourself?
I think what some people call fighting is not really fighting, but merely disagreeing.
I think what happens sometimes, is that some people think they have what others need to accept, and when they disagree, or present something that contradicts, or challenges that person's view, because the person 'so believes' they have the true wisdom, they feel a bit offended, and describe the person's offering an opposing alternative, as fighting.
I really think though, it's the case that the person is not really sure that they have true wisdom, but they want to believe it, or they convince themselves, so when someone presents something that calls that "wisdom" into question, the person feels threatened, since they would rather the person listen to them, and accept what they say.
Sometimes the person is not fully aware this is happening to them, and it's usually because they are misled - not necessarily by flesh.
A good example of this is found in the Christian Greek scriptures.
(John 9:24-34; Acts 26:4, 5)
Some of these men actually believed strongly, but they failed to realize their blindness.
"I bear them witness that they have a zeal for God, but not according to accurate knowledge. For because of not knowing the righteousness of God but seeking to establish their own, they did not subject themselves to the righteousness of God." (Romans 10:2, 3)