In what ways did Okonkwo's reaction to the white missionaries and their influence on the Ibo contribute to the theme of cultural adaptation in Things Fall Apart?

Okonkwo represents a certain way of life amongst the Ibo of Umuofia, and the rise and fall of his fortunes throughout the novel corresponds to the fitness of this way of life in varying situations. Okonkwo's values are ultraconservative: he adheres strictly to tradition and abhors deviation from it. They are also hyper-masculine: Okonkwo prioritizes strength and status over everything else, and he works hard to ensure that he has both physical strength and social clout. In the first third of the novel, before the missionaries arrive, Okonkwo's values serve him well and make him one of the leading men of Umuofia. However, the arrival of the missionaries tests these values and exposes their weaknesses.
When the missionaries come, there are three schools of thought among the villagers: those who want to join them, those who oppose them, and those who feel that compromise is possible. The same is true of the missionaries themselves: Mr. Brown believes in a kind of conversion-through-compromise and is sensitive to the existing culture of the Ibo, while Reverend Smith takes a much harder line and ultimately requires the colonial government to back him up.
Okonkwo is of the school of thought that opposing the missionaries is the only choice. There is no room for compromise, and any suggestion of compromise is in fact a betrayal of all that the Ibo stand for. Reverend Smith agrees that there is no room for compromise, and the villagers are caught between these two unyielding forces. As time goes on, then, Okonkwo's refusal to yield at all leads to the loss of everything he has worked for in his life—his refusal to allow any cooperation between the cultures or allow some level of cultural adaptation leads him to kill himself, something that is considered taboo in his culture. The arrival of the missionaries epitomizes an unstoppable force meeting an immovable object: Okonkwo does not feel that cultural adaptation is what they are aiming for: he thinks that they intend to carry out cultural eradication. In the end, however, his death symbolizes the death of hope for the kind of ultraconservative Ibo culture Okonkwo was attempting to protect. The future will be compromise and, ultimately, conversion.