Huddled with his disciples in the upper room, Jesus named a critical problem they’d soon face: “Yet a little while and the world will see me no more” (John 14:19). The trouble of that news was clear, and it confounded the disciples. After three years witnessing his miracles and soaking up his teaching, in a matter of days the world would no longer see Jesus.

With this warning of his imminent departure, Jesus made a breathtaking promise: “I will ask the Father, and he will give you another Helper, to be with you forever, even the Spirit of truth. . . . He dwells with you and will be in you” (vv. 16–17). Jesus provides a solution that more than addresses the problem of his departure. When Jesus leaves, the disciples won’t be alone; rather, the third person of the Trinity will descend on them like fire and smoke on Sinai ages before.

In fact, Jesus says, it’s better for him to go than to stay (16:7). How could that be possible? When Jesus ministered in the flesh, he exhorted, rebuked, and encouraged, but teaching alone—even divine teaching—wasn’t enough to pierce hearts hardened by the fall. If Jesus stayed, even the Sermon on the Mount would be no more efficacious than the law given on Sinai. For his disciples to have a lasting faith, they needed God’s indwelling presence to help them see the unseen.

The Spirit’s Threefold Work

At the pinnacle of Jesus’s ministry, when he appeared in his resurrected form to his disciples, he asked, “Have you believed because you have seen me? Blessed are those who have not seen and yet have believed” (20:29). These words anticipated the Spirit’s work. By granting faith, changing hearts, and empowering God’s mission, the Spirit leads believers to see what we can’t see apart from him.

1. Creating Faith

Faith, by definition, is the conviction of things unseen (Heb. 11:1)—but from where does this conviction come? God’s Spirit. His central work is to magnify Jesus, to make the crucified and resurrected Son of God beautiful before our souls’ eyes.

The church’s great theologians have stressed this point. Augustine held that the Spirit prepares the mind to grasp God’s revelation, and John Calvin elaborated on illumination: “Now we shall possess a right definition of faith if we call it a firm and certain knowledge of God’s benevolence toward us, founded upon the truth of the freely given promise of Christ, both revealed to our minds and sealed upon our hearts through the Holy Spirit.”

When Jesus leaves, the disciples won’t be alone; rather, the third person of the Trinity will descend on them like fire and smoke on Sinai ages before.

When the Spirit is sent to dwell not just with but within God’s people, we gain the help of God’s own Spirit to lead us into trusting and obeying God’s own Son. As J. I. Packer has written, “The Spirit’s message to us is never, ‘Look at me; listen to me; come to me; get to know me,’ but always, ‘Look at him, and see his glory; listen to him, and hear his word; go to him, and have life; get to know him, and taste his gift of joy and peace.’”

The Spirit prepares the heart and mind to receive God’s Word. He then further imparts the Word by focusing believing eyes on Christ. Moreover, the Spirit provides assurance that God’s Word for us is immovable: “The Spirit himself bears witness with our spirit that we are children of God” (Rom. 8:16). From faith’s inception to its eternal end, the Spirit strengthens our conviction by helping us see the unseen.

2. Effecting Change

An underrealized pneumatology can put the burden of change on the self. If we’re not relying on the Spirit, we can begin to think (at least functionally) that God provides faith at the beginning of the Christian life but offers nothing more for sanctification thereafter. Contrast that perspective with 2 Corinthians 3:18: “We all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another.” Quotations often end there, but Paul’s thought isn’t finished. He continues, “For this comes from the Lord who is the Spirit.”

God doesn’t promise us transformation and then leave us alone to be the primary agents effecting that change. The gospel is less than good news if we must achieve its benefits ourselves. Thankfully, the Spirit is active at every stage—illuminating the Word, helping us hate and turn from our sin, and deepening our vision of the Savior.

God gives faith, and he grows faith. In his Small Catechism, Martin Luther noted, “I believe that I cannot by my own understanding or effort believe in Jesus Christ my Lord or come to him. But the Holy Spirit has called me through the gospel, enlightened me with His gifts, and sanctified and kept me in true faith” (emphasis added).

The Spirit testifies to our adoption, continues convicting us of sin, and illuminates the fullness of Jesus’s beauty. He unites us to Christ and enables us to grow in his likeness. The fruit of the Spirit (Gal. 5:22–23) isn’t a list of worthy attributes to acquire in our own strength. It’s the character of Jesus himself, and it’s displayed in us because he lives in us. We can’t have faith without the Spirit, and we can’t be transformed in faith without him either (Gal. 3:3).

3. Empowering Mission

Let’s return to the upper room. “It is to your advantage that I go away,” Jesus said to his shocked and dismayed followers (John 16:7). As long as the One with power over wind and waves, with power over sin and death, was among them, their fears were tempered. But at the announcement of his departure, the disciples wondered how they’d face what was coming. How would they take the gospel to the world when the One that gospel witnessed to could no longer be seen?

When Jesus was on earth, people experienced his physical presence “in the flesh.” If you’d lived in first-century Capernaum, and you were home the exact moment Jesus passed through, you might have heard a parable conceived in God’s mind, you may have witnessed heaven’s power on display, or you may have even been touched by his healing power. All that could have been yours if you were in the right place at the right time.

By granting faith, changing hearts, and empowering God’s mission, the Spirit leads believers to see what we can’t see apart from him.

But after Jesus goes to the cross, dies, resurrects, and ascends, he gives his own Spirit to every believer. Then, Christ’s mission is unbound and advances exponentially. The world now sees Christ’s body wherever his church is found. Imbued with the gifts of heaven, the church puts Jesus’s manifold glory on display (Rom. 12:3–8; 1 Cor. 12:7–11; Eph. 4:11–13). Where the church is, there the Spirit makes Christ visible, full of grace and truth.

A biblical pneumatology helps us both to see the Spirit’s work in our lives and to bear even greater witness to what Paul calls “Christ the power of God and the wisdom of God” (1 Cor. 1:24). Faith is the conviction of what cannot be seen. The difficulty of that truth is great, but God’s answer is greater still. The Holy Spirit has already manifested and remains at work manifesting the unseen. Blessed indeed are those who haven’t seen and yet have believed.