‘Now on to the larger part of the response: First of all, Ross Jr. states that the reason tongues, prophecy, healing, etc. are titled “sign gifts” is because tongues is called a sign for unbelievers and prophecy is called a sign for believers in 1 Cor. 14:22. Ross Jr. then interprets “tongues are sign not for believers but for unbelievers” as referring to tongues as a form of evangelistic gift (I am assuming he is also considering Acts 2 were it does function as such). I do not think that is a proper understanding of 1 Cor. 14:22 and I will show why a little later, but I want to point out that the sign gifts are not given that title because of 1 Cor. 14:22. That title has been historically located in 1 Cor. 12:7-11 with Paul’s list of miraculous gifts (which is a poor title because all spiritual gifts could bear the adjective “miraculous”). 1 Corinthians 12:7 calls them the “manifestations” (showings, revealings, and signs) of the Spirit. What is significant about these signs/manifestations is that they are meant to benefit the Church and not primarily for unbelievers. This includes tongues which is part of this list of manifestations of the Spirit for the Church. This implies that one of tongues’ primary purposes is to edify the Church, not primarily to evangelize the lost.
This brings me back to Ross Jr.’s mention of 1 Cor. 14:22. He is right in taking the text at its word when it says tongues is a sign for unbelievers and not for believers. But what Ross Jr. neglects to do is consider what Paul means by “a sign to unbelievers.” Although an evangelistic emphasis could be a fair deduction if Paul’s statement stood by itself, the context of 1 Cor. 14:22 demands an entirely different meaning. Here is the context –
'Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature. 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 14:20-25 (ESV)
The verse before vs. 22 states “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” (1 Cor. 14:21). this verse is a loose quotation/summation of Isaiah 28:9-12. The context of Isaiah 28 is very helpful in understanding 1 Cor. 14:22. The situation of Isaiah 28 is that the prophets have tried to get the Israelite with words they could understand in Hebrew. However the Israelites would not listen to the prophets’ warnings, so Isaiah prophesied that soon they would hear the strange tongues of the Assyrian invaders who the Israelites would not be able to understand. In this context, strange tongues (languages) were not a sign that would help the Israelites understand and repent. Rather, they were a negative sign of God’s attitude towards the Israelites who would know that God’s judgement was on them when they heard the unknown tongues of the Assyrian army. So, in short, the tongues (languages) of Isaiah 28:9-12 are a negative sign of God’s attitude of judgement toward the Israelites and exclusion from His blessings (Grudem, loc. 1650-1667). The word ὥστε (thus, so then, so that, wherefore) thus is meant to explain how tongues is a sign for unbelievers in the New Covenant church of Corinth.
Does that mean, than, that the use of the gift of tongues that is talked about in 1 Cor. 14:22 is a negative sign of God’s attitude of judgement towards unbelievers? In short, yes, that is the message that it sends to unbelievers. In fact, it indicates that the prophecy is also a sign of God’s attitude towards believers, just not in a negative sense (1 Cor. 14:22). This is further demonstrated and explained by 1 Cor. 14:23-25. The examples that Paul provides in 1 Corinthians 14:23-25 are hypothetical in nature, but they shed a lot of light on vs. 22. First, in vs. 23 Paul shows that tongues that are without interpretation and unknown to anyone, especially the unbeliever, send the wrong signals to any unbelievers in attendance. If everyone speaks in tongues at the same time and without interpretation, the unbelieving visitor will think the whole Church is one of the crazy mystic cults that existed at the time. Instead of hearing the Gospel and being convicted of sin so that they can be brought into the fellowship of believers, the unbeliever will continue to be excluded from the New Covenant community and will still live as if God’s judgement is upon them (Fee 235-247).
Prophecy (and de facto tongues that is accompanied by the gift of interpretation), on the other hand, is described in vs. 24 and 25 as a positive sign of God’s attitude towards his people and His presence among them. whereas an unbeliever will think everyone is crazy if all speak in tongues without interpretation, If everyone in the Church prophesies, Paul says the result is the person will be convicted of their sin, everything will be made known and they will repent and confess that God is really among His New Covenant people in the Church. (…)’
source: Josh Phillips (notsohostilepentecostal).