Catechism is a program of education and faith formation that accompanies baptism. When adults convert to Christianity, they prepare for their baptism through mentoring, worshiping, and serving in the church, and through classes about basic Christian doctrine.

When a person is baptized as an infant, they are not able to learn these basics of Christianity before their baptism. Therefore, they are baptized with the understanding and expectation that they will learn and develop as a Christian as they grow into adulthood. These Christians affirm the faith of their baptism in Confirmation.