Just think, BVMFatima, a Christian by baptism, is already incorporated into Christ and the Church!
1271 Baptism constitutes the foundation of communion among all Christians, including those who are not yet in full communion with the Catholic Church: "For men who believe in Christ and have been properly baptized are put in some, though imperfect, communion with the Catholic Church. Justified by faith in Baptism, [they] are incorporated into Christ; they therefore have a right to be called Christians, and with good reason are accepted as brothers by the children of the Catholic Church."81 "Baptism therefore constitutes the sacramental bond of unity existing among all who through it are reborn."82
1272 Incorporated into Christ by Baptism, the person baptized is configured to Christ. Baptism seals the Christian with the indelible spiritual mark (character) of his belonging to Christ. No sin can erase this mark, even if sin prevents Baptism from bearing the fruits of salvation.83 Given once for all, Baptism cannot be repeated.
1273 Incorporated into the Church by Baptism, the faithful have received the sacramental character that consecrates them for Christian religious worship.84 The baptismal seal enables and commits Christians to serve God by a vital participation in the holy liturgy of the Church and to exercise their baptismal priesthood by the witness of holy lives and practical charity.85