The Deposit of Faith is the entire body of Catholic revelation contained in Sacred Scripture and Sacred Tradition, which Christ passed on to His Church through the Apostles. Paragraph 86 of the Catechism of the Catholic Church (CCC) relates that all magisterial teaching "is drawn from this single deposit of faith." Paragraph 10 of Vatican II's Dei Verbum teaches that the Magisterium, or "living teaching office of the Church ... is not above the word of God, but serves it ... and with the help of the Holy Spirit, it draws from this one deposit of faith everything which it presents for belief as divinely revealed."
In 1870 Vatican I spoke solemnly of this deposit: "The holy Spirit was promised to the successors of Peter not so that they might, by his revelation, make known some new doctrine, but that, by his assistance, they might religiously guard and faithfully expound the revelation or deposit of faith transmitted by the apostles."
It further recognized that the "meaning of the sacred dogmas" contained in the "divine deposit committed to the spouse of Christ" must never be abandoned "under the pretext or in the name of a more profound understanding."
To promulgate the CCC in 1992, Pope John Paul II wrote an apostolic exhortation, which he named Fidei Depositum, or Deposit of Faith. His opening line reads, "Guarding the Deposit of Faith is the mission which the Lord has entrusted to his Church and which she fulfils in every age." He's referring to Our Lord's Great Commission found in Matthew 28:18–20.
The Oath of Fidelity that's taken by seminary professors and Church officials as required by canon 833 reads, "I shall hold fast to the Deposit of Faith in its entirety; I shall faithfully hand it on and explain it, and I shall avoid any teachings contrary to it." Canon 750 also uses this term in defining what Catholics must believe.
Learn how the Holy Ghost moves men to accept truth in season two of Church Militant's Premium show Majesty of the Faith—Unity in Faith.