Can the sacrament of confirmation become obsolete in the Roman Catholic Church if the bishop is actually present and takes the time to do the 4th part of the baptismal rite during the baptism of the baby? Similarly, in the baptism of an adult convert to the RCC, will the baptismal rite have to be postponed if the bishop is not present at the ceremony to do the 4th part of the baptismal rite (the laying-on of hands and episcopal anointing)? Ultimately, the question boils down to this: is the Sacrament of Confirmation really necessary to complete baptism?
There are a number of approaches to answer this question. I chose to answer from St. Thomas Aquinas' SUMMA THEOLOGICA: The number of the sacraments (Tertia Pars, Q.65).
Article 1 tackled whether there should be seven sacraments and answered Confirmation was one of the sacraments instituted by which the Holy Ghost is given to strengthen us.
In Article 4. Whether all the sacraments are necessary for salvation?, St. Thomas answered that there is a twofold necessity of end:
- First, a thing may be necessary so that without it the end cannot be attained; thus food is necessary for human life.
- Secondly, a thing is said to be necessary, if, without it, the end cannot be attained so becomingly: thus a horse is necessary for a journey. (Adding: But this is not simple necessity of end.)
He then continues to answer that Baptism is necessary in the first way, simply and absolutely, while Confirmation which perfects Baptism is necessary in the second way.
cf. CCC 1285
Baptism, the Eucharist, and the sacrament of Confirmation together constitute the "sacraments of Christian initiation," whose unity must be safeguarded. It must be explained to the faithful that the reception of the sacrament of Confirmation is necessary for the completion of baptismal grace.1 For "by the sacrament of Confirmation, [the baptized] are more perfectly bound to the Church and are enriched with a special strength of the Holy Spirit. Hence they are, as true witnesses of Christ, more strictly obliged to spread and defend the faith by word and deed."2
1. Cf. Roman Ritual, Rite of Confirmation (OC), Introduction 1.
2. LG 11; Cf. OC, Introduction 2.
Borrowing loosely from St. Thomas' examples, heaven/one's salvation is the destination one needs to get to, being born would be the absolute and simple necessity toward that end, and confirmation would be the necessary horse that one would require to get to heaven/be saved. To get onto a horse, one must first be born. Being born is the first necessary step, but one must get onto the required mount to get to their destination.
(PS and from CCC 1285, the Eucharist would be the food required for the journey).
The preceding answers: is the Sacrament of Confirmation really necessary to complete baptism?
CCC 1290-1292 should resolve the rest of your post.