To expect unity just coz a group of ppl belong to a common religion is a little much.
Please do not misinterpret what I as I write as flame but with all due respect when have the Muslims been united that one expects them to unite today ? A community that cannot decide on when the moon has been sighted can hardly be expected to agree on other earthy issues.
A look at Mughal history shows that fathers were always apprehensive of their sons whom they sent away to distant places like Lahore, Bengal & Deccan and placed spies on them.Sons in turn has spied in their fathers courts. Similarly, brothers feared each other more than anyone else. Sons could not wait for their fathers to die to inherit the throne. Aurangzeb imprisoned his father who died gazing at the Taj Mahal.
Apply this to nations. There is an old adage Think Globally but act locally. Nations & leaders are responsible for their own people first and then those of their religion who live in other nations. It is not unfair of them to feel thus.
Even while traveling in a plane the air crew cautions us that in event of sudden drop in cabin pressure apply the face mask upon yourself first & then to your child because if you get incapacitated who will help the child?
Besides your parents there can be no one who shall care for you selflessly. Similarly , what you & I can feel for Pakistan & India respectively, a Sri lankan or BanglaDeshi will obviously not & should not be expected to either his priority shall always remain his own country.
Egypt cut a deal with Israel on the side , Saddam over ran Kuwait, Iran fought Iraq all because they put their own interest first. I may help my neighbors son in Math but would never do it at the cost of my own son.
Lastly, why does one expect help form another just coz we pray to same god? Do we follow all what the God tell us to do ? for if we did we would not have attacked each other.