Commenting on John 16, Luther writes:
“Here Christ makes the Holy Spirit a Preacher. He does so to prevent one from gaping toward Heaven in search of Him, as the fluttering spirits and enthusiasts do, and from divorcing Him from the oral Word of the ministry. One should know and learn that He will be in and with the Word, and that it will guide us into all truth, in order that we may believe it, use it as a weapon, be preserved by it against all the lies and deceptions of the devil, and prevail in all trials and temptations… The Holy Spirit wants this truth which He is to impress into our hearts to be so firmly fixed that reason and all one’s own thoughts and feelings are relegated to the background. He wants us to adhere solely to the Word and to regard it as the only truth. And through this Word alone He governs the Christian Church to the end” (AE 24:362).
Pentecost preachers will remember how the Spirit is inseparably bound to the Word. To look for the Spirit outside of the Word is to be lured into the realm of uncertainty where human or demonic impulses are confused with the Lord and Giver of Life. Rather, we follow the example of Peter preaching on the first Pentecost in Acts 2. When the Apostle preaches, he proclaims the fulfillment of the Old Testament (Joel and the Psalms) in Jesus crucified and risen.
The Holy Spirit has been called, “the shy member of the Trinity.” In one way, of course, the Holy Spirit is anything but shy as He empowers the prophets and apostles to speak with unparalleled boldness, giving them resilient courage in the face of persecution. But in another sense, the Holy Spirit is indeed “shy” in that He does not promote Himself, but Christ Jesus as He takes what the Son has done for us and delivers it to us, so we have access to the Father. Any talk of the Spirit which is not cruciform in shape, devoid of Christ, is suspect. The work of the Spirit is also filtered through the lens of the Cross. Hermann Sasse (1895-1976) knew this well. His preaching on the Holy Spirit remains a fine primer for our preaching on Pentecost.
This theologia crucis shines through Sasse’s sermon, “The Comforter,” based on John 15:26-16:4 and preached on Exaudi Sunday (May 29, 1938). In this sermon, Sasse develops the Biblical understanding of the Holy Spirit as comforter, the paraklete, noting it is the Spirit’s office to console the, “despairing heart in an hour of deep disappointment and bereavement.”
Sasse illustrates this with a reference to Luther and the Reformation:
“Where the word ‘comforter’ stands in our Bible, there it stands as a powerful, living witness of him, who as the Reformer of the church, and the church with him, had experienced in the days of the Reformation, because the Reformation was not well known as a shining triumph, but as a chain of very strenuous fights inside the church. For many at that time, it looked like the breakdown of the church. At that the church hardly saw anything else. In such times, Luther learned to confess: ‘I believe in the Holy Ghost’ – and he experienced what kind of comfort this faith could be.”
It is the Comforter, the Spirit of Truth, who makes the promise that the witness of Christ will not fail. The Pentecost endeavors to equip Christians in a country on the brink of war (1938!) with a courage not born of trust in princes but in Christ who has overcome the world. He is not absent from His Church but is with His Bride through the Spirit who contends against every false and lying Spirit. This means, “the Church’s witness to Christ is not merely the witness of men. It is the witness of the Holy Ghost.” He is no naked Spirit but the Spirit wrapped up with and permeating God’s Word both preached and written. Thus, this sermon has a polemical edge against those like Schleiermacher who would see the Scriptures as, “only a mausoleum of religion,”  in need of an injection of the Holy Spirit to become effective in our time. In Sasse’s preaching there is no divorce between Word and Spirit.
The Spirit works sub contraio, under opposites, to sustain and build up in the face of weakness and defeat. Sasse uses a similar approach in a Pentecost sermon based on Acts 2:1-14, “The Miracle of Pentecost,” preached two years later (May 12, 1940). Here Sasse contrasts cultural celebrations of Pentecost as the festival of springtime and new life with the grim realities of war. But the Holy Spirit, the Lord and Giver of Life, comes in the promise of the Gospel to call and gather a holy, Christian people for Christ through the forgiveness of sins. The miracle of Pentecost is not obvious. It is the miracle of faith created through the preaching of the Word of the Cross.
Here Sasse demonstrates a sharp declaration of the Law as he engages the devastation brought about by “the spirit of men” who have turned God’s good earth into a “huge cemetery.” This he says is, “what the spirit of man has brought about.” As a preacher, Sasse shuts down any and all romantic notions of what the “nobility” of the human spirit might achieve! Then as incisively as he has preached the Law, he skillfully unleashes the miracle of Pentecost as the condescension of God’s Spirit to sinful man. He reminds his hearers how the Holy Spirit is not a thing but a person and then goes on to proclaim the Spirit’s work. He is the One who brought order out of chaos in creation and He has spoken by the prophets. He is the One who descended on Christ in His Baptism and was promised to the Disciples by the Lord prior to the passion. The promise was fulfilled at Pentecost. Through his vivid recapitulation of the Biblical account of the Spirit’s work, Sasse proclaims how it is the Spirit who is given to us and for us. The work of the Spirit is to give us Jesus.
We do not soar to the heights of Heaven through some burst of divine or cosmic energy. No, the Spirit comes not by, “heroes of the faith,” but confused and trembling disciples. “The Holy Spirit comes to the place where men despair of their own wisdom and strength.” Luther’s explanation of the Third Article of the Apostle’s Creed in the Small Catechism, that we cannot by our own reason or strength believe in Jesus Christ or come to Him but that the Holy Spirit has called us by the Gospel, leaves an indelible imprint on Sasse’s sermon. The message of Pentecost is not an addendum to the Gospel, it is the Gospel. “The Holy Gospel is the message that there is forgiveness of sins in Jesus Christ and in Him alone. It is completely free, wherever this message is heard, that God the Holy Spirit is at work calling men and giving them the faith that goes to the heart.”
As a Lutheran theologian, Sasse confessed:
“As God outside of Christ always remains the hidden God, so His Holy Spirit remains hidden from us unless we find Him in the Word and in the Sacraments. And just as the revelation of God in Christ is at the same time God’s hiding in the human nature of Christ, so the Holy Spirit is deeply hidden in the means of grace. He is always an object of faith, not of sight.”
We believe in the Holy Spirit only as He gives Himself in the words of Jesus (see John 14:26). Just so in his preaching on Pentecost, Sasse does not simply preach about the Spirit but proclaims how He declares the message of reconciliation achieved by the suffering and death of the Son of God and now made ours in His words which are “spirit and life” (John 6:63).
 “The Holy Spirit in His freedom has bound Himself to the letters of the Bible so any demonstration of the Spirit and power today (I Corinthians 2:4) will happen in no other way than ‘in and through the prophetic and apostolic Word that is sure, certain, and utterly reliable’ (Bayer).” Jeffrey Silcock, “Luther on the Holy Spirit and His Use of God’s Word” in The Oxford Handbook of Martin Luther’s Theology, ed. Robert Kolb et al (Oxford: Oxford University Press, 2014), 306.
 In the memorable words of Oswald Bayer: "Those who want to search for the Holy Spirit deep inside themselves, in a realm too deep for words to express, will find ghosts, not God. They will only be amusing themselves with baseless thoughts." Oswald Bayer, Theology the Lutheran Way, trans. Jeffrey Silcock and Mark Mattes (Grand Rapids: Eerdmans, 2007), 55.
 Sermon: “The Comforter” preached on May 29, 1938 in Wittness :Erlangen Sermons and Essays for the Church: 1933-1944, translated by Bror Erickson (Saginaw: Magdeburg Press, 2013): 130. For Sasse’s earlier exegetical work on the paraklete, see Norman Nagel, “Hermann Sasse Identifies the Paralete” Lutheran Quarterly (Spring 1996): 3-23.
 “The Comforter”, 131.
 “The Comforter,” 134.
 “The Comforter,” 134.
 “The Miracle of Pentecost,” 141.
 “The Miracle of Pentecost,” 144.
 “The Miracle of Pentecost,” 148.
 Hermann Sasse, “On the Doctrine of the Holy Spirit” in Letters to Lutheran Pastors, Vol. III: 1957-1969), 209.