While not absolutely necessary for salvation, it is nonetheless recommended for all Catholics to be confirmed.
First, it concludes the sacraments of initiation which are Baptism, Communion, and, of course, confirmation. Second, the sacrament couldn’t come at a better time. While it is true that we receive the seven gifts of the Holy Spirit at Baptism, they are strengthened at Confirmation. It is like receiving a Vitamin B12 shot in order to boost one’s immune system to fight off disease.
Baptism inoculates us from original sin, but we still deal with the residue of that sin known as concupiscence. Concupiscence is a state of a weakened will, a darkened intellect, and capitulation to the passions. It sometimes takes a lifetime to overcome, or at least subdue, concupiscence.
We have to study and learn in order to grow from ignorance and prejudice. We have to constantly conform our wills to God’s will, for it is in following God’s will that we are most happy. Sometimes it takes a lifetime to realize this. We conform our wills to God’s by practicing the virtues; it takes a lot of work to keep our passions and vices in check.
At the age of puberty, everything seems to go all weak in the knees. We sometimes rebel against our parents, God, and the Church. We have to deal with new temptations. Confirmation then strengthens our gifts of the Holy Spirit at Baptism. Like at any sacrament, God gives us grace. Yet we have to cooperate with these graces in order for the sacrament to work in our lives. Think of the gifts of the Holy Spirit as wrapped presents. In order for us to enjoy the gifts and use them, we have to unwrap the box and open it.
Wisdom gives the person common sense in the natural world in order to figure out right from wrong. Understanding is a gift that helps us in the supernatural world in areas of faith and morals. Counsel creates unity of mind and heart, while fortitude gives us courage in times of trial. Knowledge in the areas of God and what He wants for us helps us to follow His will. Piety, our outlook on life, prepares us to be with God for all eternity.
Finally, fear of the Lord is a gift of holy reverence to revere God as Creator, Redeemer, and Sanctifier. These gifts all need a special boost during puberty, as well as when we become adults. There are many temptations, false prophets, and misleading voices. The gifts of the Holy Spirit give us a discerning spirit.