Any novel that takes place in colonial Africa will inevitably have to deal with the racism at the heart of the colonial project, and No Longer at Ease is no exception. Obi’s boss at the Civil Service, Mr. Green, embodies the stereotypically paternalistic racism of the British Empire in that he sees Nigerian people as fundamentally inferior to White English people. As such, he considers colonial rule a necessity and is skeptical of Nigeria’s success as an independent nation. Obi also encounters racism at the Irish convent to which his and Christopher’s Irish would-be girlfriends belong. Though the young White women enjoy Christopher and Obi’s company, they’re forced to call off the relationship after the head nun prohibits them from associating with Nigerian men.
But such dehumanization is not limited to race. The novel notably shows the prevalence of discrimination in the osu caste system of Igbo culture (a prominent ethnic group in Nigerian society). Within this hierarchy, entire bloodlines of people deemed osu—including Obi’s fiancée, Clara—are considered inferior or untouchable. The novel places all these contradictory prejudices beside one another to imply their absurdity and undercut the distinctions these prejudices allege. Ironically, the very fact that all these groups hold similar kinds of prejudices only points to the common, if flawed, human nature these groups share with one another. Obi, for his part, seems to see straight through these prejudices and pay them no heed, going so far as to attempt marriage to an osu woman—a traditionally unthinkable act among his people—yet his efforts only win him the scorn of his loved ones. The novel does allude to a slow, society-wide progress toward equality, but it suggests little in the way of meaningful action in confronting the discrimination that is present in everyday life and that is at the heart of the colonial project.
Prejudice and Discrimination ThemeTracker

Prejudice and Discrimination Quotes in No Longer at Ease
‘What I can't understand is why people like you refuse to face facts.’ Mr Green was famous for speaking his mind. He wiped his red face with the white towel on his neck. 'The African is corrupt through and through.’
Obi was away in England for a little under four years. He sometimes found it difficult to believe that it was as short as that. It seemed more like a decade than four years, what with the miseries of winter when his longing to return home took on the sharpness of physical pain. It was in England that Nigeria first became more than just a name to him. That was the first great thing that England did for him.
'What an Augean stable!' he muttered to himself. 'Where does one begin? With the masses? Educate the masses?' He shook his head. 'Not a chance there. It would take centuries. A handful of men at the top. Or even one man with vision---an enlightened dictator. People are scared of the word nowadays. But what kind of democracy can exist side by side with so much corruption and ignorance? Perhaps a half-way house—a sort of compromise.' When Obi's reasoning reached this point he reminded himself that England had been as corrupt not so very long ago.
To throw a white man was like unmasking an ancestral spirit.
That was twenty years ago. Today few white men would dream of slapping a headmaster in his school and none at all would actually do it.
‘Look at me,’ said Joseph, getting up and tying his coverlet as a loincloth. He now spoke in English. ‘You know book, but this is no matter for book. Do you know what an osu is? But how can you know?' In that short question he said in effect that Obi's mission-house upbringing and European education had made him a stranger in his country—the most painful thing one could say to Obi.
'What is a pioneer? Someone who shows the way. That is what I am doing. Anyway, it is too late to change now.'
‘Our fathers also have a saying about the danger of living apart. They say it is the curse of the snake. If all snakes lived together in one place, who would approach them? But they live every one unto himself and so fall easy prey to man.’
Obi admitted that his people had a sizeable point. What they did not know was that, having laboured in sweat and tears to enrol their kinsman among the shining élite, they had to keep him there. Having made him a member of an exclusive club whose members greet one another with 'How's the car behaving?' did they expect him to turn round and answer: 'I'm sorry, but my car is off the road. You see I couldn't pay my insurance premium.'? That would be letting the side down in a way that was quite unthinkable. Almost as unthinkable as a masked spirit in the old Ibo society answering another's esoteric salutation: 'I'm sorry, my friend, but I don't understand your strange language. I'm but a human being wearing a mask.' No, these things could not be.
He was amazed at the irrelevant thoughts that passed through his mind at this the greatest crisis in his life.
And we must presume that, in spite of his certitude, Mr Green did not know either.