Girls and women wear the cross on their clothing to protect them.
One of the first things that we learn about David’s community is a hint of the importance of religious devotion. When David meets Sophie, they are both children, and he notes the color of her clothing, including the “cross stitched to the front of the dungarees” (Ch. 1).
As we learn more about this post-apocalyptic society, religious fervor turns out to be one of the most important elements. The people of Waknuk have somehow decided that if they maintain a strict religious devotion, they can prevent similar disasters. David’s father in particular has turned to religious zealotry. He scolds a woman, telling her that she does not take her cross seriously enough.
You have sinned, woman, search your heart, and you will know that you have sinned. Your sin has weakened our defenses, and the enemy has struck through you. You wear the cross on your dress to protect you. but you have not worn it always in your heart. (Ch. 7)
The poor woman just wanted to keep her baby. She is accused of having “produced a defilement” because her baby was not perfect. In Waknuk, anyone who does not fit what they consider the perfect image of God, what they call the True Image, cannot be allowed to exist in their community. These are exiled to the Fringes.
It is into the Fringes where Sophie goes. There, the women do not wear crosses. They have been exiled by society. David is so used to seeing women wearing crosses that when he sees Sophie later without one, he finds it very surprising.
The bodice of her dress was ragged, a non-descript tawny colour, with stains on it. There were no sleeves, but what struck me most was that it bore no cross. I had never before been face to face with a woman who wore no protective cross stitched to her dress. It looked queer, almost indecent. We faced one another for some seconds. (Ch. 15)
Sophie tells Rosalind to get rid of her cross, because it “marks” her. She says that, “We women in the Fringes do not feel that it has served us very well” (Ch. 16). She also tells her that the men resent it. Religious fervor has no place in the Fringes, since it is the reason for their banishment. The women therefore do not wear their crosses.
Many dystopias include post-apocalyptic events, and the ways that people have coped with them. David’s father is an example of how religious zealotry can be harmful to a community’s ability to rebuild. The people live in fear, not of another apocalyptic event, but of him and his devotion to enforcing the True Image code. An arbitrary set of standards keeps them from living a normal life. Sophie, for example, was a normal and happy little girl until that life was stolen from her by David’s father. That is what makes this a dystopia. A life ruled by fear is hardly a perfect world.