CCC 527 Jesus’ circumcision, on the eighth day after his birth,1 is the sign of his incorporation into Abraham’s descendants, into the people of the covenant. It is the sign of his submission to the Law2 and his deputation to Israel’s worship, in which he will participate throughout his life. This sign prefigures that “circumcision of Christ” which is Baptism.3

CCC 628 Baptism, the original and full sign of which is immersion, efficaciously signifies the descent into the tomb by the Christian who dies to sin with Christ in order to live a new life. “We were buried therefore with him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.”4

CCC 1002 Christ will raise us up “on the last day”; but it is also true that, in a certain way, we have already risen with Christ. For, by virtue of the Holy Spirit, Christian life is already now on earth a participation in the death and Resurrection of Christ:
And you were buried with him in Baptism, in which you were also raised with him through faith in the working of God, who raised him from the dead. .. If then you have been raised with Christ, seek the things that are above, where Christ is, seated at the right hand of God.5

CCC 1214 This sacrament is called Baptism, after the central rite by which it is carried out: to baptize (Greek baptizein) means to “plunge” or “immerse”; the “plunge” into the water symbolizes the catechumen’s burial into Christ’s death, from which he rises up by resurrection with him, as “a new creature.”6

CCC 1227 According to the Apostle Paul, the believer enters through Baptism into communion with Christ’s death, is buried with him, and rises with him:
Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried therefore with him by baptism into death, so that as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life.7
The baptized have “put on Christ.”8 Through the Holy Spirit, Baptism is a bath that purifies, justifies, and sanctifies.9

CCC 1694 Incorporated into Christ by Baptism, Christians are “dead to sin and alive to God in Christ Jesus” and so participate in the life of the Risen Lord.10 Following Christ and united with him,11 Christians can strive to be “imitators of God as beloved children, and walk in love”12 by conforming their thoughts, words and actions to the “mind. .. which is yours in Christ Jesus,”13 and by following his example.14

1 Cf. Lk 2:21.
2 Cf. Gal 4:4.
3 Cf. Col 2:11-13.
4 Rom 6:4; cf. Col 2:12; Eph 5:26.
5 Col 2:12; 3:1.
6 2 Cor 5:17; Gal 6:15; Cf. Rom 6:34; Col 2:12.
7 Rom 6:3-4; cf. Col 2:12.
8 Gal 3:27.
9 CE 1 Cor 6:11; 12:13.
10 Rom 6:11 and cf. 6:5; cf. Col 2:12.
11 Cf. Jn 15:5.
12 Eph 5:1-2.
13 Phil 2:5.
14 Cf. Jn 13:12-16.