"I thank the good God for having so arranged our lives that our dear Armand will never know that his mother, who adores him, belongs to the race that is cursed with the brand of slavery." - Armand's Mother
This is the first time Armand and the reader realizes the baby's color is the fault of Armand, who had the established name, rather than Desiree, who adopted and had unknown birth origin. Also, this quote is very important because it was a letter from Armand's mother to his father, which means they stayed in contact. Armand's father loved an African woman, which breaks the rules set forth by the New Orleans society in which they lived.
"He thought Almighty God had dealt cruelly and unjustly with him; and felt, somehow, that he was paying Him back in kind when he stabbed thus into his wife's soul." - Armand's thoughts
Desiree had express how elated she was when Armand had stopped beating the slaves, and how pleased she had been when he had adopted a softer, gentler manner after their son was born. If anything, keeping in mind the time period, perhaps having a child with African blood was God's way of paying him back rather than being unjust.