How would an ethnocentric missionary describe the culture?
In the voice of an ethnocentric missionary (not my own, just want to make that clear...)
The Igbo are an extremely backwards society, worshipping a number of gods rather than the true god we know. They are focused on appeasing the wrath of these gods and believe that certain people are outcasts and cannot be part of their society. They even believe that twins are evil and should be left in the woods to die. They believe that the spirit of one person can come back over and over in the body of a man's children like Okonkwo's daughter.
They don't speak English or any other civilized language and lack any of the things that a modern civilization would require such as a system of laws or justice.