Confirmation ought not be treated as, or spoken of, as a sort of graduation for the simple reason that the reception of Confirmation has nothing to do with the candidate’s merit or effort. As with all sacraments, Confirmation entails the totally unmerited receiving of God’s grace. To treat Confirmation as though it is an accomplishment or that it was earned is to fundamentally misunderstand its sacramental character. (Even the effort that typically goes into preparation for Confirmation ought to be recognized as being possible and beneficial only by God’s grace.) We must remember that when it comes to grace and salvation, the initiative is always God’s.
The essential criteria for a person to receive Confirmation are that he must have been baptized and not yet received Confirmation. However, under normal circumstances, further criteria include: the ability to profess the faith and renew baptismal promises, suitable instruction, a proper disposition, and the intention to receive the sacrament.
Oil is most appropriate for the sacrament of Confirmation because it is most fitting to the sacrament’s character as an anointing with the Holy Spirit and a grace that more closely unifies the one confirmed to Christ, the Anointed One, in His offices of prophet, priest, and king.