Sister Wife by Shelley Hrdlitschka

Celeste, 14, and Nanette, 13, are sisters living in the rural community of Unity. They are part of a fictional cult that is based on real-life polygamous religious groups. Celeste and Nanette are very different in temperament, one always questioning, the other a devoted believer. When girls turn 15 in this community, they are assigned by the Prophet to an adult husband. Celeste does not want to marry an old man and thus join a household of sister wives, but no other option appears open.

The boys in this community, meanwhile, often leave (or else are kicked out) when they are in their teens. Jon, a teenager on a neighbouring farm in the community, has got Celeste thinking impure thoughts. What will she do?

Celeste's quandary is interesting enough, but I found both she and Nanette to be puppet characters, manipulated for the purpose of the plot. A third teenage girl, Taviana, who was rescued from street prostitution and given shelter in the Unity faith, is a more three-dimensional individual. The mature themes in this novel make it suitable for older teens, Grade 10 and up.

In the past year, I've read a few other teen novels featuring religious fanaticism:

I Am Not Esther by Fleur Beale

Madapple by Christina Meldrum

Unwind by Neal Shusterman