Most adults are capable of a free and informed response of faith to God's initiative of love. They have experienced the joys and challenges of life and have the capacity to question the truth and meaning of life. The catechetical formation of adults is essential for the Church to carry out the commission given the apostles by Christ.
This formation needs to be addressed to adults at different stages in the development of their faith. Many Catholic adults practice their faith and desire to deepen it. Others who have been baptized but who have not received a comprehensive catechesis or who no longer practice their faith need to be renewed through an enthusiastic preaching of the word and a vibrant re-evangelization. Still others, who are not baptized, may desire to be incorporated into the catechumenate, wherein they can gradually proceed through the stages of Christian initiation and be incorporated into the life of the Church.
Adult catechesis promotes mature adult faith: the faith of the disciple who has been saved by Christ's redemptive love and who is being continually converted to him. Adult catechesis fosters this discipleship by providing "a comprehensive and systematic presentation and exploration of the core elements of Catholic faith and practice—a complete initiation into a Catholic way of life." -from the USCCB