The sacrament of Confirmation is one of the most important ways that the Holy Spirit works in our lives. In Confirmation, God completes, strengthens and seals our baptism. We commit ourselves irrevocably to God, and He seals us, indelibly, with the gift of the Holy Spirit. This sacramental gift can never be repeated, nor can it ever be taken away. Once a confirmed Catholic, always a confirmed Catholic.
The spiritual effects of Confirmation are: (1) an increase of the sanctifying grace we received in baptism; (2) the strengthening of our faith; (3) an indelible mark of adoption imprinted by God on our immortal soul which marks us out for ever as His beloved sons and daughters; (4) the seven gifts of the Holy Spirit.
The seven gifts of the Holy Spirit: Wisdom gives us a love for the things of God, and directs our whole life to His honour and glory. Understanding enables us to fathom more deeply the mysteries of the faith. Counsel (right judgement) warns us of the tricks and deceptions played by the devil, and puts us on our guard against those things which threaten our salvation. Fortitude (courage) strengthens us to want to try and do the will of God in all the circumstances and events of our life. Knowledge enables us to discern the will of God in all things. Piety (love) makes us love God above all other things, and therefore to want to obey Him because we love Him. Fear of the Lord (reverence) fills us with a hatred for sin in all its aspects and all its effects.