1 Corinthians 14:25

the secrets of his heart are made manifest [being exposed by the cleaving sword of the Spirit-- Hebrews 4:12; James 1:23-24; comp. John 4:19; John 4:29]; and so he will fall down on his face [The Oriental mode of showing deep emotion (Isaiah 45:14; 1 Samuel 19:24). Here it indicates feelings of submission and self-abasement] and worship God, declaring that God is among you indeed. [Paul supposes the case of one who dropped into the meeting out of curiosity. If he heard many people speaking at once in an unknown tongue, he would regard the gathering as little better than bedlam (Acts 2:13), and the more he heard speaking at once, the worse it would be. Therefore the meeting would be to him void of blessing from God, and the sign without any signification, for he would hear his fellow-citizens addressing him in a foreign tongue, which was to him a mere jargon, instead of hearing foreigners address him in his own tongue, similar to the miracle at Pentecost. If, on the other hand, he heard all his fellow-citizens prophesying in his own tongue, he would be reproved by all, and the secrets of his heart would be laid bare as though he had been cross-examined by a skillful attorney. This would lead to his conversion, and so be of profit to him, and would make him a witness to the divine nature of the church, instead of one who looked upon it as a hive of fanatics. Prophetic preaching must have had great power to make men feel that they stood face to face with God, for even the faithful preaching of our day lays bare the sinner's heart. He feels that sermons are aimed at him, and is often convinced that some one has been tattling to the preacher because the life is so fully exposed by his words. It should be observed that if truth is more potent than signs, much more is it more efficacious in revivals than mere excitement or pumped-up enthusiasm.]