What are the motifs in She Said Yes: The Unlikely Martyrdom of Cassie Bernall by Misty Bernall?

Religion is very key in this book. The very title stems from the fact that Cassie said "yes" about believing in God before she was shot. Other students who claimed a belief in God were also targeted during the massacre at Columbine High School that day. However, Cassie wasn't always so strong in her faith.