What is the theme in Light a Penny Candle by Maeve Binchy?

Religion pervades Maeve Binchy's novel, Light a Penny Candle, particularly the parts set in Catholic Ireland (Free State/Republic). The fictional town of Kilgarret near Dublin is nearly entirely Catholic, the few exceptions being rich and prominent Protestants. The schools are run by the religious, catechism is part of the curriculum, and prayer before classes is normal. The O'Connor family primps Saturday nights for Sunday Mass and even irreligious Sean takes pride in their filing into a pew together.