There is a lot written on the differences amongst Muslims. Different madhabs, sects, ethnicities, organisations.
Instead of being a proof of the universality of Islam, these differences are used by some as evidence of their superiority. Or more frequently, of other's inferiority.
There was an advert recently, on one of the Islamic channels, for an Umrah/Hajj package. The voice over stated "Five times a day, all Muslims turn towards the same place", while the picture showed a montage of different Muslims all turning towards Makkah.
It's something easy to take for granted, to not appreciate this as yet further evidence of Allah's grace.
Five times a day, a sizable (and growing) chunk of the world's population, perform the same actions, speaking the same language. At any given time, I can stand on my prayer mat and know there are people all over the world doing the same.
Now that is real unity. It is something very precious that Allah has given us, and we should cherish it and remain mindful of it, instead of squandering this blessing in the pursuit of material gain.
May Allah guide and protect us all.