The Catholic Church recognizes the validity of other Christian baptisms if they involve water by immersion, pouring or sprinkling, and if they are done “in the name of the Father and of the Son and of the Holy Spirit.” If a Christian whose Baptism fulfilled these conditions seeks to become a Catholic, he or she does not need to be rebaptized, but must make a formal “profession of faith,” reciting the Nicene Creed (which is usually recited during a Catholic Mass, and expresses the fundamental beliefs of Catholics). This is done at a special ceremony called “the reception of baptized Christians into the full communion of the Catholic Church.” Normally the new Catholic receives the Sacrament of Confirmation at this time. In the case of Eastern Christians who become Catholic, no special ceremony (“liturgical rite”) is required, only a profession of faith.
