“Confirmation perfects Baptismal grace; it is the sacrament which gives the Holy Spirit in order to root us more deeply in the divine filiation, incorporate us more firmly into Christ, strengthen our bond with the Church, associate us more closely with her mission, and help us bear witness to the Christian faith in words accompanied by deeds.”
“Confirmation, like Baptism, imprints a spiritual mark or indelible character on the Christian’s soul; for this reason one can receive this sacrament only once in one’s life.”

CCC 1316-1317

Confirmation is the third of the sacraments of initiation, along with Baptism and the Eucharist.  Confirmation continues the process of initiation that was begun by Baptism.

Jesus foretold that he would send the Spirit after he was glorified (Jn 7:37-39).  This happened after his ascension to heaven, on Pentecost Sunday:

“When the time for Pentecost was fulfilled, they were all in one place together. And suddenly there came from the sky a noise like a strong driving wind, and it filled the entire house in which they were. Then there appeared to them tongues as of fire, which parted and came to rest on each one of them. And they were all filled with the Holy Spirit”    (Acts 2:2-4)

Confirmation is the special outpouring of the Holy Spirit as once granted to the apostles on the day of Pentecost.  It unites us more firmly to Christ and it increases the gifts of the Holy Spirit in us.  It gives us the grace we need to continue developing our Christian lives, to move closer to God.

The essential part of the Confirmation rite is when the bishop or priest places his hand upon the head of each individual. The bishop traces the sign of the cross on the person’s forehead—having first dipped his thumb in the holy oil called chrism—and says, “Be sealed with the Gifts of the Holy Spirit.” The newly confirmed person responds by saying, “Amen.”

Being confirmed does not imply that the candidate is completely mature in the faith.  The signing with chrism does not instantly produce maturity in the candidate.  Conversion to Christ is a gradual process to which Confirmation gives added strength.  Through it, the confirmed person is strengthened for this lifelong journey.