The Trinity explained

God the Holy Spirit

God the Holy Spirit is the third person of the Trinity, fully and truly God, and truly personal. The Spirit is not an impersonal force, an energy, or a mere influence, but a person who knows, wills, speaks, loves, and can be grieved. Scripture treats lying to the Holy Spirit as lying to God Himself, and it is the Spirit who makes the whole work of God real in us, drawing us to the Son and to the Father.

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.Acts 5:3-4 (KJV)

Truly God

When a man named Ananias lied about a gift he had given, Peter said to him, why hath Satan filled thine heart to lie to the Holy Ghost, and then, in the very next breath, thou hast not lied unto men, but unto God. In two sentences the Holy Spirit is called God without hesitation or explanation. To lie to the Spirit is to lie to God, because the Spirit is God.

The same truth runs through Scripture. The Spirit is eternal, present everywhere, searching even the deep things of God, sharing in the work of creation and of raising the dead. What only God can do, the Spirit does. What only God is, the Spirit is. The church confesses the Holy Spirit as the Lord and giver of life, worshiped and glorified together with the Father and the Son.

Not a force, but a person

It is a common mistake to imagine the Holy Spirit as an impersonal power, like electricity or wind, a divine energy God switches on. Scripture will not allow it. The Spirit does what only a person can do. He speaks, forbids, sends, and appoints. He teaches and reminds. He intercedes for us with groanings. He can be lied to, grieved, and resisted. You cannot grieve a force. You can only grieve someone who loves you.

Jesus made this personal reality vivid when He promised the Spirit. He said the Father would send another Comforter to abide with His disciples forever, and He called the Spirit He, not it: the Comforter, which is the Holy Ghost, he shall teach you all things. The word another is telling: the Spirit is another Comforter of the same kind as Jesus, a personal presence to take His place among them, not a mere power left behind. The Spirit is a Someone, the third person of the one God, as truly personal as the Father and the Son.

Distinct from the Father and the Son, yet one God

The Holy Spirit is a distinct person, not merely another name for the Father or the Son. The Spirit is sent by the Father and the Son, proceeds from the Father, and is given in the Son's name. At the baptism of Jesus the Spirit descends while the Father speaks and the Son stands in the water, three at once, plainly distinct. The Spirit prays within us to the Father; a person does not send or intercede with Himself.

And yet the Spirit is not a third God. He shares the one undivided being of God with the Father and the Son. So we confess, with the Nicene Creed, the Holy Spirit as the Lord, the giver of life, who with the Father and the Son together is worshiped and glorified. One God, three persons: the Spirit is the third of them, fully God and fully Himself, neither less than the others nor separate from them.

The Spirit who was promised and poured out

Jesus told His disciples it was to their advantage that He go away, so that the Comforter would come. On the day of Pentecost the promise was kept, and the Spirit was poured out on the church. From that day the Spirit indwells every believer. Paul writes that if any man have not the Spirit of Christ, he is none of his, and that the Spirit dwelling in us is the very life of God within.

This is why the Christian life is not mere imitation of a distant Jesus but a real sharing in the life of God. The Spirit unites us to Christ, pours the love of God into our hearts, and cries within us, Abba, Father. The Spirit is God drawing near, God within, God making the salvation the Father planned and the Son accomplished actually ours.

The Spirit had been at work long before Pentecost. He moved over the waters at creation, filled craftsmen and prophets and kings, and spoke through the prophets, as the creed confesses. What changed at Pentecost was not that the Spirit began to exist but that He was poured out on all flesh, coming to dwell not in a tabernacle of stone but in the hearts of ordinary believers, making the body of Christ His temple. The same eternal God who hovered over the first creation now works the new creation, from within.

The Spirit and the life of prayer and holiness

Because the Spirit is God dwelling within, the whole life of prayer and growth is His work. When we do not know how to pray, the Spirit Himself intercedes for us with groanings that cannot be uttered. When sin still clings, it is by the Spirit that we put it to death and are changed from glory to glory. The fruit that marks a maturing Christian, love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, is called the fruit of the Spirit, because it grows from His presence, not from our striving alone.

This means holiness is not white-knuckled self-improvement but cooperation with a Person who lives in us. We are told not to grieve the Spirit and not to quench Him, tender words that assume a real relationship. The Christian life, at its heart, is walking in step with the Spirit day by day, yielding to the God who has taken up residence within, and finding that He supplies what He commands.

The Spirit points to Christ

The Holy Spirit does not draw attention to Himself. Jesus said the Spirit would not speak of Himself but would glorify the Son, taking what belongs to Christ and showing it to us. The surest sign of the Spirit's work is not spectacle but a growing love for Jesus and a growing likeness to Him. Where the Spirit is at work, Christ is exalted and the fruit of love, joy, peace, patience, and gentleness begins to grow.

So the doctrine of the Spirit, like the whole doctrine of the Trinity, leads back to Christ and up to the Father. The Father sends the Son; the Son and the Father send the Spirit; and the Spirit brings us home to both. God is not far off. By His Spirit He has come to dwell with us and in us, and that indwelling is the beginning of eternal life.

There is deep comfort in this. The same God who is high above all, whom the heaven of heavens cannot contain, has by His Spirit made His home in the hearts of ordinary people. You do not have to travel to find Him or climb to reach Him. If you belong to Christ, God Himself already dwells within you, nearer than your own breath, teaching, comforting, and slowly making you like Jesus. The doctrine of the Holy Spirit is the promise that God has not merely visited His people from a distance but has come to live with them for good.

So when Christians speak of the Holy Spirit, they are not speaking of a vague religious feeling or a lesser divine echo, but of God Himself, the third person of the Trinity, personally present and personally at work. To be filled with the Spirit is to be filled with God. To grieve the Spirit is to grieve God. And to walk in the Spirit is to walk with God every hour of the day. The Spirit is the crown of the good news: the Father planned to save us, the Son came to save us, and the Spirit comes to dwell in us, so that the God who is love is not only above us and beside us but within us forever.

Confessed by the whole church: the Trinity is not the belief of one denomination but the historic faith held in common across Catholic, Orthodox, and Protestant Christianity, summed in the Nicene Creed of the fourth century. At the same time the church has always been humble that this truth stretches human language to its limit. God is greater than our words for Him. We confess what He has revealed of Himself, we do not claim to comprehend Him, and we hold the mystery with reverence rather than pretending to explain it away.

Related: God the Son · The Trinity and salvation · What is the Trinity? · The Trinity explained