We can clearly see that until Muslims were just Muslims and not "Shia" and "Sunni" they ruled the world (well most of it). These major categories subdivided into countless sub-categories and today you can hardly see someone who is a Muslim and that's it. Consequently, others took over leaving us disgraced.
Now that educational revolution is at its finest and we are so called intellectuals, why can't we, as the new generation, try to patch up the gaps? Why can't we respect other Muslims merely on the basis of the Kalima we share and leave the rest to be judged by Allah Ta'aala at the Promised Day. Can't we leave the controversial topics aside and be brothers as muhajireen and ansaar?
Even here at Stackexchange, people get into controversial debates developing even more hatred in their heart for their Muslim brothers.
My question is: Are we too far from uniting under one flag of Islam and what is the thing that stops us from doing so?