Jinnah, a highly Anglicized lawyer who only spoke English well, and a Muslim with little interest in the Muslim religion, moved from a united India position to making an independent Islamic state his life's goal. He sold the idea --which was originally pressed on him by others and only after much resistance on his part-- based on the fear that Muslims would be less than 2nd class citizens in an India dominated by Hindus.
Whether by discrimination (the simplest explanation) or built-in limitations, it turns out he was right. The condition of the 150 million + Muslims among India's over 1.2 billion people, 4 out of 5 of whom are Hindu, is poor. The only sector where they outperform the Hindus is in numbers in prison.
They have achieved a similar distinction in all the countries of Europe where they have i
The reason that India came to think of itself as a single country at all was the Brits. The reason India is not a single country was not the Brits, it was the Muslims. Seems they create happiness and peace wherever they go...
PS. The details of the violence and death around Partition are truly horrifying. All the worst kinds of human behavior acted out again and again. No wonder the Indians and the Pakis hate each other. Of course, the hatred was already there, beneath the surface, before Partition. The Brits kept it contained.