- Sabbath Day
- Sacramentals
- Sacraments
- Sacred Heart of Jesus
- Sacrifice
- Saints
- School
- Science
- Sedevacantism
- Seven Sorrows of the Blessed Virgin Mary
- Sin
- Single Life
- Society of Jesus
- Soul
- Spiritual Life, Spirituality
- Spiritual Reading
- SSPV (Society of St Pius V)
- SSPX (Society of St Pius X)
- St Blaise
- St Ignatius of Loyola
- St Joseph the Worker
- St Louis de Montfort
- St Patrick
- St Pius X
- St Robert Bellarmine
- St Thérèse of Lisieux
- St Thomas Aquinas
- Stations of the Cross
- Suffering
- Supernatural
