The Catholic Church is generally considered the largest single Christian church or denomination in the world. Recent Vatican statistics report more than 1.4 billion baptized Catholics globally, making Catholicism larger than any single Protestant, Orthodox, Anglican, or independent Christian body.
Why the Catholic Church ranks first
The Catholic Church is one worldwide communion organized around bishops in communion with the bishop of Rome, the pope. Because it reports membership globally, its total can be compared more directly with other individual church bodies.
Protestantism, by contrast, is a broad family containing thousands of denominations and independent churches. Combining all Protestants creates a large Christian tradition, but not one denomination.
What about Eastern Orthodoxy?
Eastern Orthodox Christianity consists of several autocephalous churches that share faith and sacraments but govern themselves through separate synods and patriarchates. They are often grouped together as one Christian tradition rather than counted as one centralized denomination.
The Orthodox total is therefore organized differently from the worldwide Catholic figure.
Global Christianity is larger than any denomination
Pew Research Center estimated about 2.3 billion Christians worldwide in 2020. That figure combines Catholic, Protestant, Orthodox, and other Christian communities.
No single denomination should therefore be confused with Christianity as a whole.
Why rankings can differ
Rankings depend on definitions. A list might compare individual denominations, broad traditions, church communions, baptized members, self-identified adults, or active participants.
For example, Anglican Communion, Pentecostalism, and Baptists can refer to families of churches rather than one centrally administered denomination.
Current answer
Using the usual definition of one worldwide church body, the Catholic Church is the largest Christian denomination, with more than 1.4 billion baptized members in recent Vatican statistics.
