Before the writing of the Holy Scriptures, that is, of the sacred texts of the Gospels, the Acts and the Epistles of the Apostles, and before they were spread to the churches of the world, the church was based on Sacred Tradition....The holy texts are in relation to Sacred Tradition what the part is to the whole.
The flow of history confirms the reality of the Gospel: the Church is filled to overflowing with sinners. Does their presence in the Church reduce, violate, or destroy her sanctity? Not in the least! For her Head—the Lord Christ, and her Soul—the Holy Spirit, and her divine teaching, her mysteries, and her virtues, are indissolubly and immutably holy. The Church tolerates sinners, shelters them, and instructs them, that they may be awakened and roused to repentance and spiritual recovery and transfiguration; but they do not hinder the Church from being holy. Only unrepentant sinners, persistent in evil and godless malice, are cut off from the Church either by the visible action of the theanthropic authority of the Church or by the invisible action of divine judgment, so that thus also the holiness of the Church may be preserved.
Of the beliefs and public doctrines entrusted to the care of the Church, there are some which are based on Scriptural teaching, others which we have received handed down in mystery by the tradition of the Apostles; and in relation to the true religion they both have the same force.