Ecclesiology means the doctrine of the church, her being, ministry, mission, and worship. The sacraments, such as water baptism and the Eucharist, are practices and doctrines of Catholic ecclesiology. Theologically, therefore, ecclesiology is the study of the Church, the origins of Christianity, its relationship to Jesus (bride and groom), its role in salvation, its polity, its discipline, its eschatology, and its leadership.

There is one body and one Spirit, just as you were called to the one hope of
your calling, one Lord, one faith, one baptism, one God and Father of all, who
is above all and through all and in all.
Ephesians 4, 4-5

Now you are Christ’s Body, and individually members of it. And God has appointed in the
Church, first apostles, second prophets, third teachers, then miracles, then gifts of
healings, helps, administrations, various kinds of tongues. All are not apostles, are they
All are not prophets, are they? All are not teachers, are they? All are not workers of
miracles, are they All do not have gifts of healings, do they? All do not speak with tongues,
do they? All do not interpret, do they? But earnestly desire the greater gifts.
1 Corinthians 12, 27-31

The gifts he gave were that some would be apostles, some prophets,
some evangelists, some pastors and teachers, to equip the saints for
the work of ministry, for building up the body of Christ,
Ephesians 4, 11-12

For just as we have many members in one body and all the members do
not have the same function, so we, who are many, are one Body in Christ,
and individually members one of another.
Romans 12:4-5

He that is not with me is against me:
and he that gathers not with me scatters.
Luke 11, 23