But Peter said, Ananias, why hath Satan filled thine heart to lie to the Holy Ghost, and to keep back part of the price of the land? ….. thou hast not lied unto men, but unto God.” Acts 5: 3, 4. In this passage we are plainly told that the Holy Spirit is God. How do you explain this obvious Trinitarian passage?
The Bible warns us not to grieve the Holy Spirit. “And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption." Ephesians 4:30. Isn't this further proof that the Holy Spirit is an individual being who can be grieved?

Answer:

These are good and popular questions. We will deal with them together as they are closely related.
There is an important principle that will help us understand these verses. The question that we need to ask ourselves is: When the Holy Spirit is grieved, who exactly is grieved? Is it God and Christ or is it someone else called 'God the Holy Spirit' ?

“And the LORD said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years. And it repented the LORD that he had made man on the earth, and it grieved him at his heart.” Genesis 6:3, 6.

This is a very plain text. We must always remember that the Spirit belongs to God; it is the Spirit of God for it proceeds from Him (John 15:26). When we grieve the Spirit of God we are actually grieving God Himself. In Acts 5 we are plainly told that the Holy Spirit is the Spirit of the Lord.

“But Peter said, Ananias, why hath Satan filled thine heart to lie to the Holy Ghost, and to keep back part of the price of the land? Whiles it remained, was it not thine own? and after it was sold, was it not in thine own power? why hast thou conceived this thing in thine heart? thou hast not lied unto men, but unto God. Then Peter said unto her, How is it that ye have agreed together to tempt the Spirit of the Lord? behold, the feet of them which have buried thy husband are at the door, and shall carry thee out.” Acts 5:3, 4, 9.

In the story of Ananias and Sapphira the same truth is again demonstrated, that when we lie to the Spirit of the Lord we are really lying to and grieving the Lord Himself, for the Lord is that spirit. Notice: “Now the Lord is that Spirit: and where the Spirit of the Lord is, there is liberty.” 2 Corinthians 3:17

This text clearly tells us who that Spirit is. Therefore, what Peter said to Ananias was really this: "by lying to God's spirit you have not lied to men, but to God Himself!" Peter was not informing Ananias that he had lied to a “God the Holy Spirit”. Rather, Ananias had lied to God (the Lord) Himself, not someone else! When we grieve the Spirit we grieve God Himself in His heart, not someone else.
The prophet Isaiah records for us an account that confirms this truth further: Isaiah 63:9-11 “In all their affliction he was afflicted, and the angel of his presence saved them: in his love and in his pity he redeemed them; and he bare them, and carried them all the days of old. But they rebelled, and vexed his holy Spirit: therefore he was turned to be their enemy, and he fought against them. Then he remembered the days of old, Moses, and his people, saying, Where is he that brought them up out of the sea with the shepherd of his flock? where is he that put his holy Spirit within him?”

Spirit of Prophecy: “How can you, oh, how can you grieve your Redeemer? How can you dishonor Him before His angels and before men? How can you grieve the Holy Spirit of God? How can you crucify the Lord of glory afresh, and put Him to open shame? How can you give occasion for Satan and his angels to exult and triumph over those who claim to be loyal subjects of Jesus Christ?” {TM 431.1}
Grieving the redeemer = grieving the Holy Spirit of God. This refers to Christ Jesus for the Spirit is His life.

“The impartation of the Spirit is the impartation of the life of Christ.” {DA 805.3}
“Christ declared that after his ascension, he would send to his church, as his crowning gift, the Comforter, who was to take his place. This Comforter is the Holy Spirit,--the soul of his life, the efficacy of his church, the light and life of the world. With his Spirit Christ sends a reconciling influence and a power that takes away sin.” {EGW, RH, May 19, 1904 par. 1}

This means that the Holy Spirit is the life and glory of Christ, not another individual being: “Jesus is seeking to impress upon them the thought that in giving His Holy Spirit He is giving to them the glory which the Father hath given Him, that He and His people may be one in God.” {EGW, 2MR 36, 37}

Thus the Holy Spirit is the life, the soul, the glory and presence Jesus Christ. This is what Ellen White means when she speaks of the Spirit of God. It is the invisible personal presence of God and Christ. The Spirit of God and Christ is their own person, not another person. Notice “God is a person and Christ is a
person.” {1SAT 343}. Therefore, the Holy Spirit is the person of God and Christ. It is the omnipresence of them; notice “He [Christ] would represent Himself as present in all places by His Holy Spirit, as the Omnipresent.” {14MR 23}

Thus, “This refers to the omnipresence of the Spirit of Christ, called the Comforter.” {14MR 179}, and so “By the Spirit the Father and the Son will come and make their abode with you.” {BEcho, January 15, 1893 par. 8}.

“Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.” “Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me.” John 14:23; Revelation 3:20

It is through the Spirit that we have a bond with the Father and Son “The sinner then stands before God as a just person; he is taken into favor with Heaven, and through the Spirit has fellowship with the Father and the Son.” {3SM 191}
“John, in the assurance of a living experience, said: "That which we have seen and heard declare we unto you, that ye also may have fellowship with us: and truly our fellowship is with the Father, and with his Son Jesus Christ." Christ, through his Spirit, is working to draw men to himself; and we, the human agents, are to co-operate with Christ; it is his power that gives efficiency to our labors.” {RH, January 6, 1891 par. 10}