14:1-5 Prophesying, that is, explaining Scripture, is compared with speaking with tongues. This drew attention, more than the plain interpretation of Scripture; it gratified pride more, but promoted the purposes of Christian charity less; it would not equally do good to the souls of men. What cannot be understood, never can edify. No advantage can be reaped from the most excellent discourses, if delivered in language such as the hearers cannot speak or understand. Every ability or possession is valuable in proportion to its usefulness. Even fervent, spiritual affection must be governed by the exercise of the understanding, else men will disgrace the truths they profess to promote.
2. speaketh … unto God—who alone understands all languages.
no man understandeth—generally speaking; the few who have the gift of interpreting tongues are the exception.
in the spirit—as opposed to "the understanding" (1Co 14:14).
mysteries—unintelligible to the hearers, exciting their wonder, rather than instructing them. Corinth, being a mart resorted to by merchants from Asia, Africa, and Europe, would give scope amidst its mixed population for the exercise of the gift of tongues; but its legitimate use was in an audience understanding the tongue of the speaker, not, as the Corinthians abused it, in mere display.