We need to tolerate each other because once one becomes absolute with their beliefs, then they close their eyes on things which are just in front of them. It doesn't matter whether if there are four religions leader successors or just one successor who is the fourth caliph or the Mahdi is already here or is yet to come or if your neighbour eats meat on the holy week. What matters most is what you believe and your impact on people around you. When you depart from this world, what remains is your memory and legacy to others. If you are good to them irregardless of their faith, color,race or gender then you will live on with them, in their hearts and in their thoughts. If you were bad, then you will just be forgotten, just a footprint in the sand, to be blown away by the wind.