Catechism number 727

The entire mission of the Son and the Holy Spirit, in the fullness of time, is contained in this: that the Son is the one anointed by the Father's Spirit since his Incarnation - Jesus is the Christ, the Messiah.
Everything in the second chapter of the Creed is to be read in this light. Christ's whole work is in fact a joint mission of the Son and the Holy Spirit. Here, we shall mention only what has to do with Jesus' promise of the Holy Spirit and the gift of him by the glorified Lord.