24 Sacred theology rests on the written word of God, together with sacred tradition, as its primary and perpetual foundation. By scrutinizing in the light of faith all truth stored up in the mystery of Christ, theology is most powerfully strengthened and constantly rejuvenated by that word. For the Sacred Scriptures contain the word of God and since they are inspired, really are the word of God; and so the study of the sacred page is, as it were, the soul of sacred theology. By the same word of Scripture the ministry of the word also, that is, pastoral preaching, catechetics and all Christian instruction, in which the liturgical homily must hold the foremost place, is nourished in a healthy way and flourishes in a holy way.
Source: Dei Verbum (Vatican.va)