Uninterpreted tongues did not benefit visiting unbelievers any more than they edified the believers in church meetings. Prophecy, on the other hand, benefited both groups.
14:20 Thinking that tongues-speaking demonstrates spirituality evidences immaturity.
"Children prefer what glitters and makes a show to what is much more valuable; and it was childish to prefer ecstatic utterance to other and far more useful gifts."334
There is a sense in which it is good for Christians to be childlike, namely in our innocence regarding evil. Still in understanding, we need to be mature (cf. 3:1-2). The Corinthians were not innocent in their behavior any more than they were mature in their thinking.
14:21 The Law refers to the Old Testament here since the passage Paul cited is Isaiah 28:11-12. The context of this passage is the Israelites' refusal to accept Isaiah's warnings concerning the coming Assyrian invasion. God said because they refused to listen to the prophet's words He would "teach"them by using their foreign-speaking invading enemy. Nevertheless even then, God said, they would not repent. Isaiah preached repentance to the Israelites in their own language, but they did not repent. Then God brought the invading Assyrians into Israel. Still His people did not repent even though God "spoke"to them of their need to repent by allowing them to hear the foreign language of this enemy.
14:22 The "then"in this verse anticipates what is to come rather than drawing a conclusion from what has preceded.
Tongues-speaking in the church signified to visiting unbelievers that the Christians were mad (v. 23).335Prophecy signified to the believers that God was present and speaking.
14:23 Paul painted a picture of the Corinthian church assembled and engaged in a frenzy of unintelligible tongues-speaking. Two types of individuals walk in. One is a believer untaught in the matter of spiritual gifts and the other is an unbeliever. To both of them the worshippers appear to be insane rather than soberly engaged in worship and instruction. The church meeting would resemble the meetings of a mystery cult in which such mania was common.
"It was strange that what the Corinthians specially prided themselves on was a gift which, if exercised in public, would excite the derision of unbelievers."336
14:24-25 If, on the other hand, the church was practicing prophesying and was receiving instruction, both visitors would gain a positive impression from the conduct of the believers. More importantly, what the prophets said would also convict them (cf. 2:14-15). Paul's description of their response came from Isaiah 45:14 (cf. Zech. 8:23) and contrasts with the unresponsiveness of the Israelites to messages God sent them in foreign languages. Prophecy would result in the repentance of visiting unbelievers, but tongues-speaking would not. These verses summarize the effects of good Christian preaching on unbelievers.
"The gift of prophesying, however successful, is no glory to the possessor of it. It is the Spirit of God, not the preacher's own power, that works the wonderful effect."337
Paul did not mean that every individual in the church would either speak in tongues or prophesy (cf. v. 23). He meant that if one of those gifts dominated to the exclusion of the other the stated results would normally follow.
"The Corinthians tend to shut their ears to prophecy because they gain more satisfaction from listening to tongues than from hearing their faults exposed and their duties pointed out in plain rational language."338
Paul permitted only intelligible utterances when the church gathered for worship because they edify believers and bring the lost to conviction of their need for salvation.
