An unbaptized person can attend the baptism and witness the event alongside the rest of the congregation. His role does not change once he is baptized. The child’s godparent remains the Catholic who was named godparent at the time of the baptism. The role of Christian witness is not meant to be confused with the role of godparent. What it is, essentially, is a way for parents to honor a close friend or relative who is a non-Catholic Christian while still retaining the sacramental discipline that only Catholics and Eastern Orthodox Christians can act as godparents. It is an ecumenical gesture, if you will. For more information, see paragraph 98 of Principles and Norms on Ecumenism, which can be found online at www.vatican.va.