Why does Patria join the revolution against the Dominican Republic dictator, Trujillo?

Patria became involved in the revolution as a direct result of something she had witnessed first-hand. While on a mission trip (Patria is the most religious of the girls), the group attending the retreat is bombed by Trujillo's men. Seeing an innocent man die for no reason changed her life, her perspective, and made her doubt her faith in God (temporarily). As a result, she came to understand that she couldn't just sit back and be a spectator. Against his better judgement, her husband Pedrito becomes involved as well.