The Holy Spirit is at work with the Father and the Son from the beginning to the completion of the plan for our salvation. But in these "end times," ushered in by the Son's redeeming Incarnation, the Spirit is revealed and given, recognized and welcomed as a person. Now can this divine plan, accomplished in Christ, the firstborn and head of the new creation, be embodied in mankind by the outpouring of the Spirit: as the Church, the communion of saints, the forgiveness of sins, the resurrection of the body, and the life everlasting.
Source: Catechism of the Catholic Church (Vatican.va)