I. The Holy Spirit is God
Job 33:4 – “The Spirit of God made me and the breath of the Almighty has given me life.” Only God is the creator of life.
Matt. 12:31; Luke 12:10 – Jesus says blasphemy against the Holy Spirit will not be forgiven. Only God can be blasphemed.
John 4:24 – God is a spirit (the Holy Spirit) and they who worship Him must worship in spirit and truth. Only God is worshiped.
John 14:16,26; 15:26; 16:7 – the Father and the Son send the Counselor, the Holy Spirit – Isaiah 9:6 – the Counselor is Mighty God.
Acts 5:3-4,9 – Peter tells Ananias that he lied to the Holy Spirit, and that he has not lied to men, but to God (the Holy Spirit).
Acts 28:25-27 – the Holy Spirit said “Go to this people and say…” – Isaiah 6:8-10 – the Lord said “Go to this people and say…”
1 Cor. 2:10 – the Spirit searches everything – Jer. 17:10 – the Lord searches the heart.
1 Cor. 3:16 – you are the temple of God – 1 Cor. 6:19 – you are the temple of the Holy Spirit.
1 Cor. 12:4-6 – there are varieties of gifts but the same Spirit, varieties of service but the same Lord, varieties of working but same God.
2 Cor. 3:6,17 – we are ministers of the covenant in the Spirit which gives life. Now the Lord (God) is the Spirit.
Heb. 10:16 – the Holy Spirit said this is the covenant I will make –
Jer. 31:33 – the Lord said this is the covenant I will make.
1 Peter 1:2 – we are sanctified by the Holy Spirit –
1 Thess. 5:23 – the very God of peace sanctifies you wholly.
“But if there is such co-ordination and unity within the holy Triad, who can separate either the Son from the Father, or the Spirit from the Son or from the Father himself? Who would be so audacious as to say that the Triad is unlike itself and diverse in nature, or that the Son is in essence foreign from the Father, or the Spirit alien from the Son?…For as the Son, who is in the Father and the Father in him, is not a creature but pertains to the essence of the Father (for this you also profess to say); so also it is not lawful to rank with the creatures the Spirit who is in the Son, and the Son in him, nor to divide him from the Word and reduce the Triad to imperfection.”
Athanasius, Letter to Serapion of Thmuis, 1:20-21 (A.D. 360).
Athanasius was not a heretic.