Using a first-person confessional and epistolary (letter) format from a naive narrator who speaks in black English dialect, Alice Walker reveals her "womanist" themes using Christian and domestic imagery in The Color Purple. In addition, Walker's structure and characterization are similar to both a slave narrative (e.g., Incident of a Slave Girl by Harriet Jacobs) and a fairy tale ("Cinderella") in order to move Celie from a rape/incest victim to a strong-willed matriarch and business woman by the end.
Walker narrates the beginning chapters in a black English dialect, addressing them to God as part of a confessional. Because she is in a male-dominated culture with no mother or protector, she exhibits a forced hopelessness and a mysoginistic attitude toward women. In fact, she has been abused so much by her step-father, Mr.__, and Harpo that she tells Harpo to beat Sophia.
Later, after three sister/fairy godmothers (Nettie, Shug, and Sophia) teach Celie to use her language and femininity, Celie begins to rebel against the patriarchy and leave her segregated marriage. Instead of addressing her letters to "God," the new, "womanist" Celie addresses them to her sister Nettie in Africa. Later, she finds domestic work in sewing which she uses to establish her Pants Store. She is even reunited with her sister and African children and bequeathed a plantation from her dead step-father, a kind of miracle ending.
So, it is Walker's use of "slave narrative" language, "womanist," domestic, and African anti-colonial themes, Christian imagery, and capitalist "fairy tale" structure that allow Celie to free herself from the male world. Even though the novel starts out as a tragedy, Walker moves it toward comedy.