one

The Church is one, holy, catholic, and apostolic

161. Why is the Church one ? 
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The Church is one Because she has as her source and exemplar the unity of the Trinity of Persons in one God. As her Founder and Head, Jesus Christ re-established the unity of all people in one body. As her soul, the Holy Spirit unites all the faithful in communion with Christ. The Church has but one faith, one sacramental life, one apostolic succession, one common hope, and one and the same charity.