God (Allah) [has been | is] testing and going to test us our faith in him in different levels, as he wants to see how will we react and remember his esistence, his unlimited power, etc.
We all decended of Adam & Hawah (Eve), but he categorised us by nationality, religion, cast, color, political status, tribe, etc, you name it what ever pops in your mind. God had reminded us that we are all equal in front of him, as he is our creator, but by him categorising us he wanted to test us if we still remember who is God? Will we follow him or not?
He sent allot of prophets and messengers with different status and merical powers to pass his message, some were continueing other's work. Prophet Mohammed ASWA was his last messenger to spread God's words and wizdoms to the world.
Our parents first choose our faith, when we grow up, and become wo(man), it becomes our responsibilty to continue on the same faith or we change it.
What I wanted to say that God testing us how will we treat others, he defined the map for us, he
told us via his holy book how to handle others depending on the categories.
That's the true and hardest test from him.