**Catechism of the Catholic Church
1212 ** The sacraments of Christian initiation - Baptism, Confirmation, and the Eucharist - lay the foundations of every Christian life. “The sharing in the divine nature given to men through the grace of Christ bears a certain likeness to the origin, development, and nourishing of natural life. The faithful are born anew by Baptism, strengthened by the sacrament of Confirmation, and receive in the Eucharist the food of eternal life. By means of these sacraments of Christian initiation, they thus receive in increasing measure the treasures of the divine life and advance toward the perfection of charity.”
ByzCath:
Your right, a baptized individual is called a candidate, a non-baptized individual is a catechumen.
But that does not change the fact that RCIA is for non-baptized individuals as it’s name shows, “Rite of Christian Initiation of Adults”.
Within the Church’s documents about RCIA you will find rites for special circumstances, such as “guidelines for preparing uncatechised adults for confirmation and eucharist (nos. 400-410) along with four optional rites which may be used with such candidates, and the rite of reception of baptized Christians into the full communion of the Catholic Church (nos. 473 –504)”.
Again, a baptized person is a Christian.
A validly baptized Protestant is a Christian, but is he a formal member of Christ’s Church? No, he isn’t. The Protestant is only in imperfect communion with Christ’s Church, and by making a profession of the faith, and by receiving the other two Sacraments of Initiation, the Protestant can become a formal member of the ONE, Holy, Catholic and Apostolic Church.The Catholic faithful are required to profess that there is an historical continuity — rooted in the apostolic succession — between the Church founded by Christ and the Catholic Church: “This is the single Church of Christ… which our Saviour, after his resurrection, entrusted to Peter’s pastoral care (cf. Jn 21:17), commissioning him and the other Apostles to extend and rule her (cf. Mt 28:18ff.), erected for all ages as ‘the pillar and mainstay of the truth’ (1 Tim 3:15). This Church, constituted and organized as a society in the present world, subsists in
subsistit in] the Catholic Church, governed by the Successor of Peter and by the Bishops in communion with him”. With the expression
subsistit in, the Second Vatican Council sought to harmonize two doctrinal statements: on the one hand, that the Church of Christ, despite the divisions which exist among Christians, continues to exist fully
only in the Catholic Church, and on the other hand, that “outside of her structure, many elements can be found of sanctification and truth”, that is, in those Churches and ecclesial communities which are not yet in full communion with the Catholic Church. …
The Church is the “universal sacrament of salvation”, since, united always in a mysterious way to the Saviour Jesus Christ, her Head, and subordinated to him, she has, in God’s plan, an indispensable relationship with the salvation of every human being. For those who are not formally and visibly members of the Church, "salvation in Christ is accessible by virtue of a grace which, while having a mysterious relationship to the Church, does not make them formally part of the Church, but enlightens them in a way which is accommodated to their spiritual and material situation.
DECLARATION “DOMINUS IESUS”:
ON THE UNICITY AND SALVIFIC UNIVERSALITY OF
JESUS CHRIST AND THE CHURCH
CONGREGATION FOR THE DOCTRINE OF THE FAITH