Hindu,Muslim,Sikh,Christanity,Bhuddhist and Jains,these are the religion which prevails the planet(Of course there are some more tribes and followers of some other belief...it is just a crude analysis).
Considering Hindus only,there are various kind of Hindus,in fact every state in India has its own kind of Hindus.
Then there are further classifications like thakur,rajput,vaishyas etc. etc.
Then there are further more divisions into small groups or chunks of on the various of like mindedness,same status,even same qualifications etc. etc. and etc.

In the history of human kind and today...
We may not be able to understand the nature,
we may not have not learned to treat others without being biased,
even we are not able to understand ourselves but...
we have managed to perfectly divide humans and humanity based on various caste,creed,region,religion and biased thinking.