Full communion

In Christian ecclesiology, full communion is a relationship between church organizations or groups that mutually recognize their sharing the essential doctrines. As a practical matter for most Catholics, this affects whether or not a member of one Church may partake of the Eucharist celebrated in another, and for priests, whether or not they may concelebrate the Eucharist with priests of another Church. In each case, if the two Churches are in full communion, then they may.

For the Eastern Orthodox Church, the Roman Catholic Church, the Oriental Orthodox churches and the Church of the East, full communion exists only between Christians who form a single church. Protestants understand full communion as instead a matter of practical relations among denominations that nonetheless fully retain their distinct identities.

Roman Catholic Church

Full and partial communion

The Roman Catholic Church makes a distinction between full and partial communion. Where full communion exists, there is but one church. Partial communion, on the other hand, exists where some elements of Christian faith are held in common, but complete unity on essentials is lacking. For instance, the Roman Catholic Church sees itself as in partial communion with Protestants, and in much closer, but still incomplete, communion with the Orthodox churches.