Celie tells Shug that she no longer writes to God—she writes to Nettie. This letter is addressed to Nettie. Celie says that God would never listen to a poor black woman—that God has not listened to her throughout her life. Thus she desires to write to someone, like Nettie, who might actually one day read her letters.
This is an important shift. Celie began writing letters to God when she was being abused, told to stay quiet, and had no one else to turn. Now she does have family and connections, and so she writes to them.
Celie and Shug have a discussion about religion, after Celie decides to stop writing to God. Shug says that, just because she (Shug) has behaved immorally in her life, she is not without religion, and she tells Celie not to blaspheme against the God that she (Shug) believes in. Shug says she believes God wants people to be happy, and that is the God she worships: not the God that white say she ought to believe in.
Shug introduces a new, spiritual dimension for the divine. Although Shug does not live her life strictly in accordance with Biblical teachings, she nevertheless lives according to the idea that God wants love, just like humans, and that we show our love for God by loving others.
Shug asks Celie what her God looks like, and Celie replies that her God is a white man. Shug says this is the problem—that God can be whatever she wants, and that Celie ought not to internalize a conception of God that is foreign to her, created by white people. Celie thinks this make sense, in light of what Nettie once told her: that Jesus had hair "like lamb's wool."
Another important moment, commingling ideas of race and religion in the novel. Moment's earlier Celie had rejected God because she had been taught to see God as white, as being like the people who had oppressed her and her people. But Shug makes Celie see that it's not God she needs to reject, but rather her old idea of God. That her God doesn't have to be the white people's God. That she can have a God who does listen to her.
Shug goes on to say that God is inside her and all around, and that she, when younger, went from believing that God was a white man, to believing that God was found in nature, even found in human pleasure. Celie has trouble believing this at first, thinking that perhaps Shug is the one blaspheming, but Shug replies that all God wants to do is love, and be loved.
Shug sees God as being everywhere, in the beauty of the world and the pleasure of experiencing that world. It's ironic that Olinka culture shares this sense of God being found everywhere in nature. And Nettie, Samuel, and Corrine first arrive among the Olinka to stamp out this idea, and to replace it with the idea of a single Christian God. Of course, Nettie comes to feel differently, too, and to develop sentiments that echo Shug's here.
Celie continues, in the letter, by saying to Nettie that she is trying to find God outside of man—to find God in nature, in rocks and trees and grass. But this is hard work, because it involves un-learning a lifetime of white Christian teaching. Celie says she is doing her best to be spiritual in this new way, Shug's way.
Celie takes Shug's ideas to heart. In seeing God as something that is not linked to white men, she also de-legitimizes any claim that white men have to power over her through religion.