A dominant theme of Achebe's book has to do with the changes the tribe goes through as a result of the transition from isolation to inclusion. In the beginning, the tribe is alone with only their knowledge of their own beliefs. Every aspect of their culture was homogenous, nothing foreign had ever intruded. Then the tribes were divided by an alien influence: Christians. This led to confusion, adaptation, and eventually inclusion into a broader society. In some ways, this change is similar to changes that have occurred in western civilization. .
One change that is occurring in western civilization has to do with the development of technology. As a result of some of these developments, we have gone from multitudes of relatively isolated communities and individuals to a more cohesive, global community. Two examples of this progression are transportation and information innovations such as air travel and the internet. Because of these innovations we have gained relatively easy access to people and communities in other cultures from which we would have been otherwise isolated.
Okonkwo's tribe is Isolated in the sense that it is not aware of Christianity or the white man. Its inhabitants, including Okonkwo, live amongst themselves and worship inanimate objects. This belief, or religion, seems to be based around the survival of the tribe. For example, the god of the land allows a harvest of good crops if the proper rituals are performed during the sacred week. This is good for crops and insures the need of food for the people. The tribe worships a religion that is inanimate. There is no prophet or bible to study from, or no churches to attend, but this spiritual connection brings unity and comfort. Also, there is no equality between the males and females. Women are subservient to men. The religion, again, was not designed as a philosophy and does not say explicitly how to treat companions or humans in general.