Who are the most zealous Christians and why are they eager to attack Ibo customs and religion in Things Fall Apart?

The most zealous Christians are the ones labeled osu or outcasts by the rest of the tribe. These ones have the most to prove because all their life they have been taunted and seen as less than average men by the rest of the tribe. When they get a chance to be on the other end, to be seen as superior by mocking the rest of the tribe, they take it, due to their insecurity with their own self worth.