This paper studies the ambivalent use of Christianity in Solomon Northup’s autobiography Twelve Years A Slave in the context of colonialists interest. Northup laboured for twelve years under different slave owners with one thing in his mind that one-day God will do justice. Several times he is being exploited by the owners by the name of God. Religion is a part of culture where faith and ritual are important but this faith and ritual might be imposed by a dominating or superior culture. An analysis of this memoir with a postcolonial reading, especially under the notion of Aime Cesaire’s ideas from Discourse on Colonialism and Edward Said’s ideas from Culture and Imperialism, will help to examine the religious ambivalence created by a particular culture, imposed by European priests. This memoir is an illustration of religious ambivalence where Christian religion is a part of colonial instrument which has generated hope among people and sometimes people used it for exploitation.