Why do we have many different language?

Different languages have come about because, language the oldest and most beautiful discovery of the human species, was in the old world,got isolated as the pastoral people moved from place to place in search of greener pasture. If only they had today's "communication systems" there would have been one language. But if they had today's technology(Communications or others)there needn't have been so much of people's movement too. In this movement, languages not only broke down into several tongues, they became the centers of sub-cultures and sources of many emotional connections. The idea of how languages became different and became one cause for the confusion is caught beautifully in The Bible by a parable which gave us the idiom: a perfect babel. It is not impossible that, in the remote future when wars, terrorism and such other crude methods of settling disputes cease to exist,a common languge would emerge and stay on. Perhaps then "The Tower of Babel" can be demolished.

well about this i personally feel that the there are different religion that's why we have different languages if there are one language then all people should belong to same religion as far my mind is concern in this

Over centuries, people in different regions developed their respective languages for communication purposes. For some time, Esparanto was invented and considered by some people to be the approach to promote peace and eliminate conflicts, but this man-made language is not mentioned very much any more. As long as we have the urge to be open minded and to accept different cultures, language should not a big issue.