• The Holy Spirit descends and enables the disciples to speak in other tongues, with bystanders saying "We hear them declaring the wonders of God in our own tongues" (Acts 2:6, 11).
• Here, the gift clearly involves real human languages that the speakers had never learned.
  • The Greek word for "tongues" (glossai) can mean "languages," underscoring that these utterances had linguistic content (BDAG, s.v. glossa 2).
• The event is also marked by visible "tongues as of fire" resting on each believer, a sign of the Spirit’s empowerment (Acts 2:3-4).

• Speaking in tongues is also Spirit-prompted speech in languages unknown to the speaker.
• In Corinth, it differs from Pentecost in that tongues are ordinarily unintelligible to the audience without interpretation. Without the gift of interpretation, the content remains unknown to the congregation and even to the speaker (1 Cor 14:13-14).
• Many scholars describe Corinthian tongues as "language-like" vocalisations that sound like real speech but require divine interpretation for meaningful content in the assembly (Fee, The First Epistle to the Corinthians NICNT; Thiselton, The First Epistle to the Corinthians NIGTC; Carson, Showing the Spirit).

Biblical "tongues" are Spirit-inspired utterances in languages the speaker has never learned.

• At times (Acts 2) they are recognised human languages heard and understood by listeners
• At other times (e.g. Corinth) they are language-like speech that can only edify when God provides an interpretation (1 Cor 14:5, 13, 27-28).
• In every case, they are a form of communication in the Spirit given by God’s enablement rather than produced by the speaker’s own mind or training.

The Purpose of Tongues: Private and Public

Privately: Prayer, Praise, Edification

• The primary use of tongues is prayer, praise, and personal edification.
• The direction is to God, not to people. "One who speaks in a tongue speaks mysteries to God" (1 Cor 14:2). Most read this as God-ward prayer/worship rather than human-directed instruction (Fee 2014; Carson 1987; Thiselton 2000).
• At Pentecost they were "declaring the mighty works of God" (Acts 2:11), which indicates praise.
• There is a sort of inner dynamic where "my spirit prays" even when the mind does not grasp the content (1 Cor 14:14-15).
• Paul’s encourages frequent desiring of Tongues - "I thank God that I speak in tongues more than all of you" (1 Cor 14:18); "I wish you all spoke in tongues" (14:5). These imply frequent private use.

Publicly: Interpreted Edification

• When public, the goal shifts to church edification, which requires intelligibility.
• A tongue spoken aloud in the gathering must be interpreted so all can understand and be built up (1 Cor 14:5, 27-28).
  • The order of this is that two or three would speak, one at a time. "Let someone interpret" and if there is no interpreter, keep silent in the assembly and speak to self and to God (1 Cor 14:27-28).
  • Who interprets? The speaker may pray to interpret his own utterance (1 Cor 14:13), or another believer with the gift of interpretation may do so (1 Cor 12:10-11). The Spirit gives both tongue and interpretation (Carson 1987; Fee 2014).
• When interpreted, a tongue becomes a communicable message that edifies like prophecy, because the congregation can understand it (1 Cor 14:5).
• Important note: because tongues are addressed to God (1 Cor 14:2), interpretations generally take the form of prayer, praise, or thanksgiving to God rather than a direct oracle from God to the congregation.
  • Paul’s example: giving thanks in a tongue requires interpretation for others to say "Amen" (1 Cor 14:16-17).
• By contrast, prophesy is speech from God to people for upbuilding, encouragement, consolation, and conviction (1 Cor 14:3, 24-25). Both edify, but intelligible prophecy is prioritised in the gathered church because it directly communicates God’s word to listeners (1 Cor 14:1, 5, 19; Carson 1987; Thiselton 2000; Fee 2014).

Tongues as a Sign for Unbelievers

• Foreign speech to Israel functioned as a judicial sign of unbelief. In Isaiah, unintelligible Assyrian speech often showed covenant displeasure, not spiritual vitality (Thiselton 2000; Ciampa & Rosner 2010).
• Paul then applies the principle: "tongues are a sign not for believers but for unbelievers" (1 Cor 14:22). The point is not that tongues evangelise, but that uninterpreted tongues signify divine judgement or outsiders’ status when they encounter the church and fail to understand (Carson 1987; Fee 2014).
• The result is that if outsiders enter and hear only unintelligible speech, they conclude believers are "out of (their) minds" (1 Cor 14:23). But intelligible prophecy may expose the heart and lead to worship, "God is really among you" (14:24-25).

Why Intelligibility Matters

• The chapter’s controlling principle is edification through clarity: words, meaning, and mind engaged (1 Cor 14:6-12, 15-19, 26-28, 39-40). Paul requires interpretation for public tongues so the church is instructed rather than confused (Fee 2014; Thiselton 2000).
• The implication is that when unbelievers or uninformed guests are present, the church should prefer intelligible communication. Uninterpreted tongues in public worship are out of place because they hinder understanding and mission (1 Cor 14:23-25, 27-28).

Pentecost as a Different case

• Acts 2 shows known human languages declaring "the mighty works of God" that drew a diverse crowd’s attention (Acts 2:6-11).
  • The tongues were not the sermon; they prepared the ground for Peter’s intelligible proclamation (Acts 2:14-41).
  • Most recognise this distinction between praise in many languages and subsequent preaching (Keener 2012; Marshall 1980; Bruce 1990).
• Simply put: at Pentecost, tongues functioned as a positive sign that gathered hearers for the gospel, but in Corinth uninterpreted tongues in worship risked signalling judgement or madness.

Additional Notes

• There are many different accounts of spontaneous speech in an unknown-to-the-speaker language that served cross-cultural witness. While true, doctrine should be built on Scripture rather than experience. These are best seen as sovereign exceptions, not norms we can turn into doctrine (Keener 2011).
• Ordinary means of evangelism: clear proclamation of Christ is God’s usual pathway to faith (Rom 10:14-17). One should value openness to the Spirit and the apostolic rule of intelligibility and love in gathered worship (1 Cor 14:27-28, 39-40).

Orientation of Tongues: God-ward Prayer and Praise

To summarise the nature and purpose of tongues:

1. tongues are fundamentally directed toward God (in prayer, praise, blessing) and,
2. serve for personal spiritual enrichment or,
3. when interpreted, for the church’s edification.
   Tongues have a sign value (like miracle-signs). Used rightly, they display God’s power; used without interpretation or out of order, they warn of judgement and can confuse unbelievers.