Four years ago the Archbishop of San Francisco assigned me to the Star of the Sea, a large and beautifully Catholic building. Its statues, stained glass, marble altar and altar rail were still intact, but, like the entire parish, languishing in dilapidation. Mass attendance had dropped precipitously since the Italians and Irish began moving to the suburbs in the 1980s. The aggressive secularism of the last decade seemed to seal the fate of this once thriving parish, and the archdiocese began talking about a “merger”.

The other day a priest who had served 10 years ago at Star of the Sea remarked on the parish’s “amazing revival”. Mass attendance has been growing annually at 12 per cent, and income has more than doubled. We’ve planted flowers and shrubs, installed new lighting, restored the marble sanctuary and flung the doors wide open to the city. The parish school begins an Integrated Classical Curriculum (consisting of grammar, logic and rhetoric) this autumn, and parishioners are caring for the homeless and advocating for the elderly and unborn.

Mother Teresa famously said, however, that “we are called not to success but to fidelity”. Success and fidelity are essentially different categories, motivated as they are by different ends. While not demanding success, the Lord does expect the fruit of fidelity. His first command, to “be fruitful”, has never been abrogated, and “every branch that does not bear fruit will be cut off” (John 15:2). Christ promises 30, 60 and a hundredfold fruit to those who faithfully sow his Word. There is a way of measuring the revival of a parish, but it is not “success”. It is fruitfulness.

Mass attendance and activities are good fruits, but the best fruit of any parish is healthy Catholic families. Are parishioners getting married and staying married? Are they having children? Are spouses faithfully living their sacramental vows, and is this fidelity reflected in their children’s lives? As healthy families are generational and need years of cultivation, a pastor may not see this fruit during his tenure. But he will see swifter fruits, such as increasing Mass attendance, blossoming schools and a zeal to serve the poor.

We have seen both short and long-term fruits by building on St Prosper of Aquitaine’s three laws, the lex orandi (relating to prayer), lex credendi (belief) and lex vivendi (living). The way we pray determines the way we believe, which determines the way we live. Fidelity to these three laws provides Beauty, Truth and Goodness.

In his first encyclical, Deus Caritas Est, Benedict XVI defined the three munera, or essential tasks, of the Church, governed by Prosper’s three laws. “The Church’s deepest nature,” he wrote, “is expressed in her three-fold responsibility: of proclaiming the word of God (kerygma-martyria), celebrating the sacraments (leitourgia) and exercising the ministry of charity (diakonia). These duties presuppose each other and are inseparable.”

All parishes put time and money into all three tasks, but some focus disproportionately on kerygma (Catholic schools, dynamic preaching, social media), others on leitourgia (where either “progressive” or “traditional” liturgy becomes an obsession), and others on diakonia (“social justice” parishes). Mother Teresa, it seems to me, struck a healthy balance between orandi, credendi and vivendi. Her Missionaries of Charity pray four hours a day, but also study and teach continuously, and hit the streets daily in “wholehearted and free service to the poorest of the poor”.

Let’s consider how a parish can balance these three essential tasks.

The parish is first of all a school of prayer, in the words of John Paul II. It teaches prayer best by following the lex orandi which make liturgy beautiful. The Curé of Ars began his pastorate by spending money on new vessels and vestments for his country parish. Making everything in and around our churches bright, beautiful and clean is a priest’s first business. It’s as simple as following the General Instruction to the Roman Missal and reading the 2001 Vatican Instruction Liturgiam Authenticam closely.

Music, as the queen of the liturgical arts, requires particular attention. In music you get what you pay for, and people will pay for what they get. At one point we were spending 25 per cent of our budget on music, but our offertory increased by 50 per cent.

This school of prayer must also provide the Sacrament of Penance, because we all make mistakes and can learn from them. Young adults flock to the parish mostly because we put a priest in the box at every Mass, and an hour every Tuesday night.

Eucharistic Adoration seals the deal. We put $300,000 (£226,000) into a Eucharistic Chapel that burns brightly day and night. It’s worth every penny, because people need a beautiful place to pray before the Eucharistic Christ. The sacred liturgies must stir the soul with deep beauty.

The parish must also be a school of God’s Word. Following the lex credendi through fidelity to the Church’s doctrine revives a parish because “my people are destroyed for lack of knowledge” (Hosea 4:6). After Beauty, we seek Truth.

In our parish, priests teach children and priests teach adults, along with lay instructors. Besides the forthcoming Integrated Classical Curriculum, our school uses the Catechesis of the Good Shepherd, both proven effective in transmitting the kerygma. Homilies are expected to be good enough for publication and website posting, and our communications staff broadcast the Word through extensive use of social media, including a weekly bulletin for older folks. “How will they believe if they have not heard?” asks St Paul (Romans 10:14). The parish’s homilies, catechesis and school must stir the mind with deep truth.

Finally, the parish is a school of service, following the lex vivendi. Beauty leads to Truth, and Truth leads to Goodness. Charity begins in the rectory, with priests taking meals together and praying a weekly “family rosary”. I require my priests (there are currently four of us) to pray lauds and vespers together every day in the church. Lay people always join us.

Having ordered our lives together in charity, we can serve others. Our parish serves the very poorest of the poor by praying every week outside an abortion clinic. We feed the homeless every day from the rectory and join Mother Teresa’s Sisters regularly in the streets. A stewardship council articulates what St John Paul II called the “Law of the Gift”, which motivates all charitable giving. According to this law, we increase in the measure that we give, because life is about giving, not getting. The parish’s spirit of charitable service must stir the heart with goodness.

Structuring the parish on the three laws of praying, believing and living guide the parish’s three essential tasks of Sacrament, Word and Charity. But there is a fourth way to revive a parish: let no parish forget Our Lady.

“Is this the face that launched a thousand ships?” the poet spoke of the beautiful Helen. The Trojan War lasted 10 years, but we are engaged in a much longer struggle. It must be the face of Mary that launches pastoral action. My very first act in a new parish is to consecrate it to Our Lady. I myself lead the rosary processions, the Angelus before Mass and the rosary after Mass. No parish devoted to Our Lady will fail to bear fruit, because she is the mother of all the living.

Fr Joseph Illo is pastor of Star of the Sea Parish, San Francisco