Same-sex orientation or practice is held to bar full membership or participation

This group gathers the denominations of Christianity, the world's largest religion, whose two-thousand-year history has produced a wide family of churches divided by doctrine, authority, liturgy and history. The major fault lines are the split between the Eastern and Western churches (traditionally dated 1054) and the Reformation of the sixteenth century.

The browser will find the great communions, Roman Catholicism, the Eastern and Oriental Orthodox churches, and the many Protestant families (Lutheran, Reformed, Anglican, Baptist, Methodist, Pentecostal and more), together with older and smaller bodies. The entries describe each branch's distinctive teachings and origins without treating any one as the standard against which the others are measured.

Christian denominations share the core confession of Jesus Christ while differing over questions such as church authority, the sacraments, the role of scripture and tradition, and the path of salvation. Some divisions are ancient and doctrinal; others are national, cultural or the result of later revival and reform.

The atlas presents each denomination in its own terms, noting where it stands on the questions that separate it from others and how it understands its relation to the wider Christian body, from claims of unique continuity to the ecumenical movement that seeks reunion.