One of the arguments used by cessationists to prove that speaking in tongues in private prayer or in the corporate assembly (even with interpretation) is not a valid experience today is their insistence that tongues in the NT were evangelistic. That is to say, this spiritual gift was given by God primarily, if not exclusively, to enable a believer to share the gospel with non-Christians who spoke a different language.
But there is no evidence that tongues-speech was designed to evangelize unbelievers. That isn’t to say God couldn’t use it to save souls, or even as a form of pre-evangelism, but that’s not its primary purpose. When people spoke in tongues they declared “the mighty deeds of God” (Acts 2:11; observe the same phrase in Acts 10:46 and 19:17). The people don’t hear an evangelistic message but rather worship. It is only Peter’s preaching that brought salvation. Here, as elsewhere, we see that the primary purpose of tongues-speech is address to God, whether it be praise or prayer (1 Cor. 14:2, 14). And when the household of Cornelius spoke in tongues, far from questioning the sanity or stability of these believing Gentiles, Peter concluded that they were saved and thus eligible to be baptized in water no less than had they been Jews who accepted Jesus (v. 47).
In the Book of Acts, some, but not all, who received Christ as Savior spoke in tongues immediately upon their conversion. There are several instances of conversion in Acts where no mention is made of speaking in tongues. This doesn’t prove they didn’t. But neither should one conclude that they did.
Only in Acts 2 are tongues explicitly said to be human languages not previously learned by the speaker. Nowhere in Acts did speaking in tongues function as an evangelistic tool, nor do we ever find an apostolic exhortation that it be used for that purpose. If tongues was primarily given to evangelize the lost then someone must account for why in the three explicit references to tongues in Acts, only once (Acts 2) are unbelievers present.
What, then, are we to make of 1 Corinthians 14:21-25? Here Paul writes:
“In the Law it is written, ‘By people of strange tongues and by the lips of foreigners will I speak to this people, and even then they will not listen to me, says the Lord.’ Thus tongues are a sign not for believers but for unbelievers, while prophecy is a sign not for unbelievers but for believers. If, therefore, the whole church comes together and all speak in tongues, and outsiders or unbelievers enter, will they not say that you are out of your minds? But if all prophesy, and an unbeliever or outsider enters, he is convicted by all, he is called to account by all, the secrets of his heart are disclosed, and so, falling on his face, he will worship God and declare that God is really among you” (1 Corinthians 14:21-25).
Let’s try to make sense of the scenario that Paul envisions. According to v. 23, Paul envisions a public assembly: when “the whole church comes together.” The purpose of such a gathering is not only to praise and pray but even more so to instruct and encourage and build up the members of the body. Therefore, everything that happens must be intelligible. This is why he will later insist on interpretation of all tongues speech, so all can understand and all can be edified.
The problem in Corinth is that numerous people were all speaking in uninterpreted tongues simultaneously: imagine the confusion and the chaos. No one understands, no one is instructed. This isn’t to say they aren’t speaking in genuine tongues. This isn’t to say they aren’t praising God and praying and giving thanks. They are, but to no one’s benefit other than their own.
Into this situation unbelievers enter. It is here that Paul quotes Isaiah 28:11 and applies it to the circumstances in Corinth. But to make sense of the passage in Isaiah one must look at an earlier warning of God to Israel in Deuteronomy 28:49. There we read that if Israel violates the covenant, God will chastise them by sending a foreign enemy, speaking a foreign tongue. Thus, confusing and confounding speech was a sign of God’s judgment against a rebellious people. This is the judgment that Isaiah says has come upon Israel in the 8th century b.c. when the Assyrians invaded and conquered the Jews (cf. also what happened in the 6th c. BC, Jer. 5:15).
Many cessationists argue that God is judging unbelieving Jews in the first century, the sign of which is language they can’t understand (i.e., tongues). The primary if not sole purpose of tongues, therefore, is to signify God’s judgment against Israel for rejecting the Messiah and thereby shock them into repentance and faith. Tongues, so goes the argument, are a “sign” to unbelievers of God’s judgment. Since tongues ceased to function in this capacity when Israel was dispersed in 70 a.d., the gift was valid only for the first century.
But there are numerous problems with this view. First, if tongues are meant to serve as a “sign” to unbelievers, why does Paul counsel against their use when unbelievers are present (v. 23)? Also, even if tongues served as a sign of God’s judgment, nowhere does the NT restrict or reduce that gift to this one purpose. Simply because tongues are said to function in one capacity does not mean it cannot function in others. Tongues also serve the “common good” of the body of Christ (1 Cor. 12). In 1 Corinthians 14:4, the gift of tongues edifies the individual in private prayer. We must avoid the error of reductionism (i.e., identifying one valid use of a gift and then reducing it to that alone, to the exclusion of all other possible uses).
Furthermore, if tongues-speech was not a spiritual gift for the church at all, why did Paul ever allow it to be exercised and used in the church? If interpreted, tongues-speech was entirely permissible. But this seems difficult to explain if its only or primary purpose was to declare judgment against unbelieving Jews.
Again, if uninterpreted tongues were designed to signify God’s displeasure and judgment, he would not need to provide the accompanying gift of interpretation. This latter gift makes sense only if tongues-speech is profitable and beneficial to Christians in the assembly.
For all these reasons, I conclude that the view that tongues is only (or even primarily) a sign of judgment on first-century unbelieving Jews is unconvincing.
What, then, is the principle that Paul finds in Isaiah 28:11 that applies to Corinth (and to us)? It is this: when God speaks to people in a language they cannot understand, it is a form of punishment for unbelief. It signifies his anger. Incomprehensible speech will not guide or instruct or lead to faith and repentance, but only confuse and destroy. Thus, if outsiders or unbelievers come in to your meeting, most likely out of spiritual curiosity or perhaps even in the pursuit of the gospel, and you speak in a language they cannot understand, you will simply drive them away. You will be giving a "sign" to them that is entirely wrong, because their hardness of heart has not reached the point where they deserve that severe sign of judgment.
So when you come together (1 Cor. 14:26), if anyone speaks in a tongue, be sure there is an interpretation (v. 27). Otherwise the tongue-speaker should be quiet in the church (v. 29). Prophecy, on the other hand, is a sign of God’s presence with believers (v. 22b), and so Paul encourages its use when unbelievers are present in order that they may see this sign and thereby come to Christian faith (vv. 24-25).
Therefore, Paul is not talking about the function of the gift of tongues in general, but only about the negative result of one particular abuse of tongues-speech (namely, its use without interpretation in the public assembly). So, do not permit uninterpreted tongues-speech in church, for in doing so, you run the risk of communicating a negative sign to people that will only drive them away.
From this we may then conclude that the cessationist is simply wrong when he argues that tongues were evangelistic or that they were designed to serve as a sign of judgment to unbelieving Jews.