When the day of Pentecost had come, they were all together in one place. And suddenly from heaven there came a sound like the rush of a violent wind, and it filled the entire house where they were sitting. Divided tongues, as of fire, appeared among them, and a tongue rested on each of them. All of them were filled with the Holy Spirit and began to speak in other languages, as the Spirit gave them ability.
Now concerning spiritual gifts, brothers and sisters, I do not want you to be uninformed. You know that when you were pagans, you were enticed and led astray to idols that could not speak. Therefore I want you to understand that no one speaking by the Spirit of God ever says ‘Let Jesus be cursed!’ and no one can say ‘Jesus is Lord’ except by the Holy Spirit. Now there are varieties of gifts, but the same Spirit; and there are varieties of services, but the same Lord; and there are varieties of activities, but it is the same God who activates all of them in everyone. To each is given the manifestation of the Spirit for the common good.
For Jews and early Christians, these "spirits" were typically hostile or deceptive powers. Consulting them was a dangerous business. So the coming of the Holy Spirit, or the Spirit of God, can be heard as a contest between these hostile (or "demonic") spirits and the power of God to produce truth, faith, and virtue in us. In Luther's version of the baptism rite, the pastor says "Depart, unclean spirit, and make way for the Holy Spirit." We aren't empty vessels waiting for God to fill us up; we're the site of many influences working through our words and actions.
Paul suggests something a little different. You were "led astray by idols that could not speak," he tells his hearers. The pagan gods aren't voices at all; they're silent blocks of wood and stone that human beings fill up with their own words and meanings. This is not a new idea (we see an entertaining version of this view in the Greek version of the Book of Daniel, in a story called 'Bel and the Dragon'). But it is a powerful one. People looking for a message from an oracle or a soothsayer will be willing to believe even the shoddiest human ventriloquism. By contrast, the Spirit of God reveals and confirms the truth, and activates "gifts" within the believer that she would not otherwise have. If the idols merely speak some version of human conventional wisdom back to us, the Holy Spirit speaks unexpected power.
So as we approach this festival, it's worth asking ourselves: what voices speak through us? It can be as simple and obvious as an internet 'meme' that we repeat or vary, pushing along a fragment of thought without weighing it ourselves. Or it can be as subtle and profound as a whole system of assumptions and stereotypes that we pick up little by little and often aren't even aware of. It may also be the voice of charity, mercy, and grace that we know comes from outside and beyond us--the Holy Spirit. And at the same time, we can ask what words do we seek from idols? What are we willing to believe? What gifts do we seek at hands other than God's?