"Human beings live both inside themselves and outside themselves. They live in those they love and in those who love them. We are relational. Only in and with others am I myself. But sin is the disturbance of relationship. Therefore sin is not restricted only to the individual. So in is always an offense that touches others, that alters the world and damages it."
Pope Emeritus Benedict XVI
Great quote, @mikel. Do you know the exact reference? I may use it in future writing.