1 Corinthians 14:4 He that speaketh in an unknown tongue edifieth himself; but he that prophesieth edifieth the church.
The person who speaks in an unknown tongue only edifies himself. This brings up an interesting problem. If a person doesn’t know what he is saying, (as tongues speakers themselves say that they do not even know what they are saying), how then does the tongues speaker edify himself? How can HE receive edification if HE doesn’t even understand what he is saying? His only edification is in the building up of himself in the eyes of the onlookers, deceiving them into thinking that he has some “special” gift that they do not or that they “cannot comprehend.” When a man talks in tongues, if he doesn’t understand what he is saying himself, he isn’t kidding anybody but himself. He’s not edifying himself. He is just scrambling his mind.
But, a person who prophesies gives a clear message to others, increasing their understanding for their benefit. He imparts to them understanding, encouragement, and comfort. His purpose is to help others, NOT himself. He doesn’t exhort himself and he doesn’t comfort himself. Prophecy edifies the whole church.