Decision of electing first Khalifa was taken in 632 AD. Battle of Karbala took place in 680 AD. It is 2103 and most of the participants are not even remotely related to the people involved in those disputes. Nevertheless Shias & Sunni clash in almost every day in nearly every Muslim country especially so in Iraq, Syria & Pakistan.
Karl Marx was right when he said Religion is like an alluring sun, which revolves round a man until he begins to revolve himself
I beg forgiveness when despite being Muslim from generations, I find it difficult to get excited about events that happened more than thousand years ago. Only think I feel is pity for the poor souls that are killed and anger for the people who exploit this difference.
Omar Khayyam must also have felt deep anguish about such bigotry when he stated:
Quomi mutafakkerand andar rahe deen
Quomi bagumaan uftadeh dar raahe yaqeen
Mi tarsam az aankeh baang ayad roozey
Kaaye bekhabraan rah no aan ast was na een.
Meaning nations are thinking much about religion and fall into the trap of certainty about the correct path. I am afraid that one day a voice will shout (from heavens) ye ignorant people, truth is neither that nor this one"