Grace, mercy, and peace to you from God our Father, and from our Lord and Savior, Jesus Christ. Amen.
No, let me try that again: Grace, mercy and peace to you from God our Father, our Lord and Savior, Jesus Christ, and from the Holy Spirit, the Comforter, Helper, and witness of the Truth. Amen.
It’s Pentecost, after all. It’s the Holy Spirit’s day to shine. For once, He gets to step out of the shadows, come in from the cold, and take center stage in our attention. By all rights, this really shouldn’t be such a rare occurrence, should it? After all, the Holy Spirit is truly and fully God, just like the Father and the Son. We shouldn’t shortchange Him or push Him off into the margins of our faith.
If anything, we should realize and constantly remember that it is only on account of the work of the Holy Spirit that we have faith in God, and in the person and work of Jesus Christ for our salvation, at all. You remember it, don’t you?
“I believe that I cannot by my own reason or strength believe in Jesus Christ, my Lord, or come to Him, but the Holy Spirit has called my by the Gospel, enlightened me with His gifts, sanctified and kept me in the true faith.” 
Your faith is certainly your faith, a personal connection to the suffering, death, and resurrection of Jesus. But it is not your faith alone; it is a common confession shared with true believers of every time and place, brought to you and given to you by the Holy Spirit. Theologians distinguish these aspects of our relationship with God as being the faith which believes, and the faith which is believed.
In both instances, however, we know and confess that this takes place by the Spirit working through the proclaimed Word and through the Sacraments instituted by Christ for the forgiveness of our sins and the strengthening of our faith.
There are those among our Christian brothers and sisters who will argue that, unless you have received the Holy Spirit in a dramatic and visible way, like the apostles and other believers did on that long-ago Pentecost Day recorded in the book of Acts, your faith is not genuine, or is at least incomplete. Yet this not only runs against the testimony of the Holy Scriptures, it turns the reception of faith into a self-centered competition of sorts. It becomes a game of “Can-You-Top-This?” among believers, each seeking to have the most spectacular of Spirit-given experiences.
Now, none of us can say with certainty that the Holy Spirit cannot bestow faith upon people in fantastic ways, for He is not bound by our notions. He has certainly worked dramatically on many occasions recorded for us in the Bible. We know also that He can work when and where He wills—not to mention how. But to expect—or even to demand—that He work according to a particular formula of our insistence is nothing more than blasphemy: Sinful creatures sitting in judgment of holy God, determining what He can, should, or must do.
Consider this, however: Both the Old Testament and the New have hundreds of instances of people being brought to faith in the one, true God. Some of these are undoubtedly quite dramatic, it’s true. Yet there are plenty of instances where—apart from any visible or audible appearance of God, or even the performance of any tangible miracle—people are brought to faith. Here before me today sit many dozens of examples of those granted saving faith through the Holy Spirit’s work, too.
I venture to guess that most, if not all, of you did not see tongues of fire or hear people speaking in languages previously unknown to them when you heard the Gospel and became believers in Jesus as your Savior. You did not writhe on the floor in convulsions, drink poisons, or handle serpents, either. Were such things true and genuine measures of coming to faith, we would expect the history of the Christian Church to be bulging at the seams with such stories.
Yet even in apostolic times, and in the centuries which followed, the Church realized that the power of the Holy Spirit to bring people and keep people in faith did not depend on dramatic outward signs. It depends solely on the power of God, usually working in quiet, humble, perhaps even what many would consider boring ways: In the telling of the story of God’s faithfulness and love in giving His Son as the sacrifice for our sins. In the granting of His grace in water and Word, confession and Word, bread and wine and Word.
See the common element there? It’s always the Word—the logos—Christ Himself, made flesh by the Spirit in His mother, Mary. Made real and accessible to us in the Scriptures through the inspiration of the Holy Spirit. What greater evidence of God’s power is there than the miracle that divine words spoken by sinful men can make you believe the unbelievable? Can eradicate your sins? Can make you brothers and sisters and children of God? Can lead you to gifts and acts of service to your neighbor?
It’s all the more miraculous because God didn’t have to “Wow!” you with impressive theatrics to make you believe. He simply spoke, from Father and Son to Spirit; from Spirit to prophets and apostles; from Scripture to pastors and teachers and parents and others to you. And, through His words, He made His promises a reality for you.
Pentecost itself is the fulfillment of a promise from God, is it not? A specific promise, one of many made by Jesus to His disciples on the night when He was betrayed into the hands of sinful men. It’s important for us to remember that while all of God’s promises are for the benefit of His people and to increase their trust in Him, sometimes their fulfillment is intended to affect a particular individual or group at a particular time and place. We shouldn’t attempt to extrapolate and extend all of His promises to ourselves, for He gives us the ability to differentiate those which are specific and which are available and applicable to all.
There in John’s gospel, Jesus is speaking to those who have been with Him from the beginning of His ministry. The giving of the Spirit in the unique way in which it was manifested on that Pentecost Day was intended to enable the apostles to bear witness in a powerful, visible, dramatic way for the benefit of their hearers in Jerusalem.
It benefits us, too, of course. Not because we have (or ought to expect) similar experiences, but because it demonstrates the power of God to work things in His own way.
It also provides us the opportunity to trust the witness of the apostles about that Pentecost Day, given to us through the Scriptures. Having not seen the tongues of fire, nor heard the sound like a rushing wind, or Galileans speaking directly to us in English, we have the blessing of being those who have not seen, and yet believe. We have a faith based not in evidence, but in trust. That is: Not in demonstrable, irrefutable proof, but genuine faith. As the author of Hebrews put it, “faith is being sure of what we hope for and certain of what we do not see.” 
In the middle of today’s Gospel lesson, Jesus indicates that part of the Holy Spirit’s work is to “convict the world.”  Now, in our modern use of language, we might think that to “convict” means to prove beyond a reasonable doubt some set of facts, as in the legal sense of convicting someone of a crime. But to convict really means to generate or solidify a belief; to determine what one holds to be true. So Jesus is telling the soon-to-be-apostles that the Holy Spirit will, as He says a few verses later, “guide you into all the truth.” 
Jesus mentions three things that the Helper, the Holy Spirit, will convict the world about: Sin, righteousness, and judgment. Let’s look at each of those three things. Jesus’ words tell us how the Holy Spirit will convict the world: “concerning sin, because they do not believe in me; concerning righteousness, because I go to the Father, and you will see me no longer; concerning judgment, because the ruler of this world is judged.” 
The conviction concerning sin, because the world does not believe in Jesus, means that the primary cause of sin is the rejection of faith—the rejection of God as our Creator, Redeemer, and Sanctifier. For who among us, truly believing every moment that God demands perfection and threatens us with eternal damnation and punishment for straying from His ways, would dare to sin?
We sin because we are sinful, of course, and we have nothing originating within us that can prevent us from following that path and rebelling against God and His Law. It is among the works of the Holy Spirit, then, to remind us daily of those failings, present the Law to us, and prick our consciences to realize that if those sins are held against us, we are doomed.
The conviction concerning righteousness, because Jesus has gone to the Father and we see Him directly no longer, means that it is apart from visible proof of God’s presence among us in the person of Christ that we have faith in Him and what He has done for us. It is apart from having personally seen His incarnation, birth, preaching, miracles, torture, crucifixion, death, resurrection, and ascension that we are still convinced of these truths by the witness of the Holy Spirit, through the words of the apostles.
In the work of the Spirit, we are granted faith and kept in faith, made righteous time and time again as He “calls, gathers, enlightens, and sanctifies, the whole Christian Church on earth, and keeps it with Jesus Christ in the one, true faith…”  daily and richly forgiving your sins.
The conviction concerning judgment, because the ruler of this world is judged, means that we hold to the truth that the devil no longer holds sway over us. Unbelievers will not receive and know this truth until it is too late for them, but we know and trust it to be a reality for us, even now. In Luther’s words in the lyrics of A Mighty Fortress:
This world’s prince may still
Scowl fierce as he will,
He can harm us none,
He’s judged; the deed is done. 
What comfort to know, then, that we, too, have been convicted by the Holy Spirit concerning sin, righteousness, and judgment! By His work, we are turned from our sin and driven to repentance. By His work, we are given trust that, having not seen Jesus ourselves, the truthful witness of the prophets and apostles lives on in the Holy Scriptures. The powerful words of God create and sustain faith in our hearts, forgiving our sins and strengthening our bonds with Father, Son, Holy Spirit, and with one another. And by the Holy Spirit’s work, we know that Satan and his followers are judged for their unbelief, and we who believe will not be judged and found wanting, for Jesus has taken the blame and the punishment for our sins. He has given us His righteousness, so we may stand before the judgment throne, faultless and pure.
Having been guided into the truth, then, rejoice that God has chosen to give you His Holy Spirit, in ways that may seem bland and mundane but are no less powerful and miraculous in their effect than anything recorded in the Scriptures. Follow His leading in speaking God’s word; speaking not of your own authority, but bearing witness to what you have been granted by the Spirit, in Word and in truth.
“And it shall come to pass that everyone who calls upon the name of the Lord shall be saved.” 
In the name of the Father, and of the (X) Son, and of the Holy Spirit, our Helper and Comforter. Amen.