The Apostles’ Creed doesn’t elaborate on the person or work of the Holy Spirit, but that doesn’t mean he’s somehow less important than the Father or the Son. Both the Old Testament and the New Testament teach that the Holy Spirit is God. The Bible’s opening verses, in fact, picture the Holy Spirit hovering over the chaos of unformed matter before creation. So the Spirit, together with the Father and the Son, was there in the beginning, giving shape to the cosmos.
In addition, the Holy Spirit convicts us of our sin and rebellion against God. The Spirit breathes life into our hearts and removes our spiritual blindness, giving us eyes of faith. The Spirit is the one who helps us see and understand that Jesus is the Savior who has shown us the grace and love of the Father. And throughout our lives the Spirit continues to work in our hearts, gradually making us more like Jesus and prompting us to serve him in the world.