What Does it Mean to Speak in Tongues?

Acts 2

4 And they were all filled with the Holy Spirit and began to speak with other tongues, as the Spirit was giving them utterance.

Mark 16

15He said to them, "Go into all the world and preach the good news to all creation. 16Whoever believes and is baptized will be saved, but whoever does not believe will be condemned. 17And these signs will accompany those who believe: In my name they will drive out demons; they will speak in new tongues; 18 they will pick up snakes with their hands; and when they drink deadly poison, it will not hurt them at all; they will place their hands on sick people, and they will get well."

1 Cor 14

1 Follow the way of love and eagerly desire spiritual gifts, especially the gift of prophecy. 2 For anyone who speaks in a tongues does not speak to men but to God. Indeed, no one understands him; he utters mysteries with his spirit 3 But everyone who prophesies speaks to men for their strengthening, encouragement and comfort. 4 He who speaks in a tongue edifies himself, but he who prophesies edifies the church. 5 I would like every one of you to speak in tongues but I would rather have you prophesy. He who prophesies is greater than one who speaks in tongues unless he interprets, so that the church may be edified.

6 Now, brothers, if I come to you and speak in tongues, what good will I be to you, unless I bring you some revelation or knowledge or prophecy or word of instruction?

13 For this reason anyone who speaks in a tongue should pray that he may interpret what he says. 14 For if I pray in a tongue, my spirit prays, but my mind is unfruitful.

18 I thank God that I speak in tongues more than all of you. 19 But in the church I would rather speak five intelligible words to instruct others than ten thousand words in a tongue.

20 Brothers, stop thinking like children. In regard to evil be infants, but in your thinking be adults.

21In the Law it is written:
   "Through men of strange tongues
      and through the lips of foreigners
   I will speak to this people,
      but even then they will not listen to me," says the Lord.

22 Tongues, then, are a sign, not for believers but for unbelievers; prophecy, however, is for believers, not for unbelievers.

23 So if the whole church comes together and everyone speaks in tongues, and some who do not understand or some unbelievers come in, will they not say that you are out of your mind? 24 But if an unbeliever or someone who does not understand comes in while everybody is prophesying, he will be convinced by all that he is a sinner and will be judged by all,

27 If anyone speaks in a tongue, two—or at the most three—should speak, one at a time, and someone must interpret. 28 If there is no interpreter, the speaker should keep quiet in the church and speak to himself and God.

39Therefore, my brothers, be eager to prophesy, and do not forbid speaking in tongues. 40 But everything should be done in a fitting and orderly way.

Acts 10:44
No sooner were these words out of Peter's mouth than the Holy Spirit came on the listeners. The believing Jews who had come with Peter couldn't believe it, couldn't believe that the gift of the Holy Spirit was poured out on "outsider" non-Jews, but there it was—they heard them speaking in tongues, heard them praising God.

Acts 19:5
And they were. As soon as they heard of it, they were baptized in the name of the Master Jesus. Paul put his hands on their heads and the Holy Spirit entered them. From that moment on, they were praising God in tongues and talking about God's actions. Altogether there were about twelve people there that day.

1 Corinthians 13:8
Love never dies. Inspired speech will be over some day; praying in tongues will end; understanding will reach its limit. We know only a portion of the truth, and what we say about God is always incomplete. But when the Complete arrives, our incompletes will be canceled.