In Celie's first letter to God, she referred to herself as a girl, in the sense that she was chronologically a girl, and, moreover, she emphasized that she was a "good girl." Other children who are Celie's age may still be literally and chronologically "girls," but we realize here that Celie is a woman. At fifteen, she is pregnant and she is carrying her father's child. Moreover, Celie's current pregnancy is not even Celie's first pregnancy.
Celie has already had another baby — a year ago, when she was fourteen. What happened to it? Celie's mother asks this question on her deathbed, and Celie answers that "God took it." She loves her mother so much that she wants her to think that the baby was stillborn.
This explanation to her mother is not what Celie believes in her heart, however. She believes that her father — the baby's father, Fonso — killed the baby, but because Celie's mother dies such a painful, loud death, with Fonso moaning and sitting beside the bed, and with Celie nursing and caring for the other children, what else can Celie do but lie? She doesn't want to hurt her mother, and, in addition, we see that Celie fears that Fonso will kill this second baby, just as he did the first one. She doesn't want to burden her mother, as she is dying, with this terrible knowledge.
Celie's compassion for her mother is clearly not that of a "girl"; she has the understanding and compassion of a woman. Celie's childbearing and her witnessing the agonizing death of her mother have forced her to become a woman long before her time.
Celie's mother dies, screaming at Celie and cursing her, and yet Celie never tells her that Fonso is the father of both babies.
Unfortunately, with her mother gone, Celie has no protection from her father's sexual attacks. And since we, the readers, realize this, Fonso's pleas to his wife of "don't leave me, don't go" seem fraudulent. How could a man "cherish" his wife and sexually abuse their daughter — and then slay his own child? Perhaps he wants to conceal his incestuous relationship with his daughter. Perhaps he wants to decrease the number of mouths he has to feed. At present, his motivations are unclear. But at this point, we are not deeply concerned with Fonso's motivations. We are far more concerned with Celie's plight: living with a father who rapes her, expecting another baby, and living with the almost certainty that her father killed their first child.
These first two letters to God are some of the most powerful letters in American literature, and certainly no other major American novel has begun with such unexpected narrative dynamite.