Adult catechesis is part of the Spiritual Formation of adult disciples of Jesus Christ. As baptized members of Holy Mother Church, St. Paul encourages us to "not be conformed to this world but be transformed by the renewal of your mind, that you may prove what is the will of God, what is good and acceptable and perfect" (Romans 12.2).
Our own consciences and beliefs have to be shaped by the Word of God outside of us as it comes to us: at Mass (via the lectionary, or lectio selecta) or private, contemplative study (lectio divina); in short, we have to constantly learn to think sacramentally as Catholic Christians in the face of so much hostility in the world. Adult education provides opportunities for such spiritual growth and formation.