“I believe in the Holy Ghost.”
The Holy Ghost is the third person of the blessed, holy, and undivided Trinity. He is the Lord and giver of life who proceeds from the Father and the Son and, who with the Father and the Son, together is worshipped and glorified.
This is what and who the Holy Spirit is, but we would not be able to know or confess that without the Spirit’s particular office and work: Revelation
It was the Spirit who spoke by the prophets and apostles through the miracle of inspiration, causing holy men to speak as they were moved (1 Peter 1:21) so that their words became worthy of the title “God-breathed” (2 Timothy 3:16).
That man might benefit from these sacred writings, the Spirit also opens the eyes, ears, and hearts of God’s elect that they might come to a saving knowledge of Christ (John 16:12-16).
Lest the believer then doubt or finally fall, the Spirit also takes up residence in his heart to assure him of his adoption, to help in his weakness, and increase hope as he looks for the fullness of redemption to appear (Romans 8).
Believe in the Spirit today and listen what he has said to the churches (not through tongues, dreams, or prophetic ecstasies), but through that more sure word of prophecy that is found in scripture alone.