The Church is the supernatural family of God; the communion of all believers united in Him.
The Church is both human and divine, earthly and heavenly.
God has used human people, rituals, and institutions to gather His people and accomplish His plan of salvation.
God's people are united in His Church through the bonds of Christian love as well as three visible bonds of community: the bond of apostolic succession through the bishops who maintain the fraternal harmony of God's family; the bond of a common celebration of worship particularly in the Sacraments; and finally, the bond of professing the one faith received from the Apostles.
There are four chief characteristics of the Church, known as the marks of the Church:
one, holy, catholic, and
apostolic.
The Church is
one because that is what Jesus intended. He prayed that we would all be one even as He is one with the Father.
The Church is
holy in the sense it is united with Christ, sanctified by Him, and endowed by Him with the fullness of the means of salvation.
The Church is
catholic, meaning universal, in the sense Christ is present in her throughout the world, and because the Church has been sent by Christ to bring all humanity into communion with Him.
The Church is
apostolic because it is founded on the Apostles and faithfully hands on the teachings of the Apostles. The Church continues to be guided by the successors of the Apostles, the Bishops.