This book briefly covers the story of the origins of Catholicism, its distinct Christian moral code, and its place in the modern world.

Catholicism is one of the world's most practiced religions, and it has a long history, filled with scandal, transformation, and competition.

According to the Australian Jesuit priest, author, and educator Gerald O'Collins, Catholicism can retain its place among the great world religions if the Church implements reforms previously codified by the Vatican II — the 21st ecumenical council of the Roman Catholic Church.

O'Collins taught theology at the Jesuit Theological College, Victoria, and has published numerous books on the topic, including titles such as Jesus, The Tripersonal God, and Lost in Translation. O'Collins now serves as a research professor at St Mary's University College, Twickenham, UK.

In Catholicism: A Very Short Introduction is part of Oxford University Press's Very Short Introductions series.

O'Collins introduces the Catholic view of God, the development of the Catholic moral code, its spread across continents, and its relationship with modernity.