The theme of "Where the Mind is Without Fear" by Rabindranath Tagore is freedom from colonization and what it takes to achieve that.
Tagore lived in India during British Crown rule of the country. According to the BBC, Britain ruled India from 1858 until 1947. Tagore was born in 1861 and died in 1941. He never lived in an India that wasn't ruled by the British—and yet dreams of what his country could be if it was free, as described in "Where the Mind is Without Fear."
The British rule of India created a system that prevented many Indian people from gaining education or positions of power in the country. Tagore speaks to that when he says:
Where the mind is without fear and the head is held high
Where knowledge is free
Where the world has not been broken up into fragments
By narrow domestic walls
He's aware that his own people are being kept from knowledge—and not because it's the right thing to do. Instead, it's caused by the "dreary desert sand of dead habit" that British rule became in India.
Tagore believes that education, working together, and "ever-widening thought and action" can change things. That's why he says that the world he describes is "that heaven of freedom" and asks "[his] Father [to] let [his] country awake."
The entire poem functions as a prayer. He's addressing his father, but not the one he was born to. Rather, it appears that he's addressing God and asking that India, his nation, be released into the world he describes.