St Alphonsus Liguori might not be a household name—at least in most households—but he should be. This 18th-century Italian is founder of the Redemptorists and earned his place as a Doctor of the Church, and even the impressive title ‘Prince of Moral Theologians’.

What is moral theology? If theology is the ‘science of God’, our inquiry into the God who reveals himself, then moral theology is our inquiry into the moral significance of human actions in light of our eternal destiny.

Born in 1696 in Naples, Alphonsus grew up in an era captured by the Jansenist spirit. Jansenism was an influential religious movement, characterised by its rigour and an intense focus on personal discipline, seeing in this austerity the only real path to holiness. It was this association of harsh discipline with holiness that Alphonsus wanted to resist.

One of his classic devotional works is called The Practice of the Love of Jesus Christ, and he begins with these words:

Some, says St Francis de Sales, make perfection consist in an austere life, others in prayer, others in frequenting the Sacraments, others in alms-deeds. But they deceive themselves: perfection consists in loving God with our whole heart.

Here we have, in some sense, the heart of Alphonsus’ moral theology. The Gospel is the wonderful news that God never gives up on us and has been doing everything within his power to win the affections of the human heart. From the beauty of creation to fashioning us in his image and likeness; from the vastness of space with its stars and planets and moons, to the taking on of our own human nature in Jesus of Nazareth—he offers us all of this to capture our hearts and win our love. To fail to see this is to fail to see the Gospel.

None of this, obviously, means that Alphonsus was not serious about the moral weight of human actions. From an early age, he committed himself to never wasting a single moment of his life. At the age of 13, he began studying law (six years before the usual age) and by 16 had earned his doctorate. By 19 he was practicing law. He liked to fence and ride horses and play cards and attend the opera.

He was a man of passion and strong spirits, and he brought this into his priestly ministry, recognising the great calling that lay upon every person: to become a saint. And becoming a saint involves loving God with our whole being.

However, loving God in this way requires more than human effort. The sacraments are vital for this, he writes—the Eucharist especially, which he sees as a divine fire capable of warming the coldest heart. ‘This Sacrament,’ he said in that same book, ‘above all others, inflames our souls with divine love.’ Abiding in the presence of this fire is key to growing and deepening the love to which we are called.

There is a beauty and simplicity to St Alphonsus’ writings, reminiscent of St Thérèse of Lisieux (even though she was born nearly two centuries later). According to St Alphonsus, this call to love is not only for the monastics or the cloistered or the missionaries. It is for everyone, even those living a simple life in the world, not performing great deeds. He professes a profound belief that every aspect of life, no matter how unimportant we think it is, can be made into love:

Purity of intention is called the heavenly alchemy by which iron is turned into gold; that is to say, the most trivial actions (such as to work, to take one’s meals, to take recreation or repose), when done for God, become the gold of holy love.

By some mysterious grace—a kind of heavenly ‘alchemy‘—every part of our lives can become the gold of holy love if we offer it to God and for God. No part of our lives is insignificant to God; no aspect of our being is unimportant. Everything is called by love to love.

For this reason alone, St Alphonsus should become a household name, occupying a special place in the devotional life of our families. The Practice of the Love of Jesus Christ especially is a work of great beauty—a book that, if we let it, could change our lives.

The feast day of St Alphonsus Liguori is celebrated by the Catholic Church on 1 August.