answer is in your question.
you are right that we are not fallowing the path of our beloved prophet hazrat Muhammad (s.a.w.w).

From basic lessons of Quran on of is, that all human beings should take care of each others self and promote goodness,and choose the right way for the living.
And when we fallow the path of Quran then ultimately we reach at the true solution of our and whole world's problems.
There is a big mistake which is repeating it self from the beginning of life is that we make the differences or we can say we choose the differences ,but Gods messenger came here for the end of these differences which we created on different names,and these differences makes the division
and if we are divided this is because of our difference "you are irani i am Pakistani ,you are Arab i am afghani etc etc"
you see we think after our cast class and nationality that we all are Muslims.
we don't want to see similarities which are between all us we just trying to search out what is the difference between me and others
we are just trying to prove that we or others are different,and it is against the teaching of our religion,
we all are equal to ALLAH.
IN few worlds i just want to say we are not following the teachings of our religion that's why we are not together and that's the reason we are fighting with our self.

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Life is what happens to you while you’re busy making other plans. –John Lennon