21 In the law it is written, With men of other tongues and other lips will I speak unto this people; and yet for all that will they not hear me, saith the Lord. 22 Wherefore tongues are for a sign, not to them that believe, but to them that believe not: but prophesying serveth not for them that believe not, but for them which believe.
Paul connects tongues to Isaiah’s sign language and calls tongues a sign to unbelievers.
Acts gives observable accounts of people receiving the promised Spirit. Those narratives supply the Bible’s clearest pattern for recognizing Spirit reception.
Apostolic teaching distinguishes the initial sign of tongues when the Spirit is received from the later congregational gift that requires interpretation.
Paul’s question ‘do all speak with tongues?’ concerns distributed gifts in the assembled body, not the repeated initial sign in Acts.
Start with the promise, then compare Acts 2, 10, and 19. Use 1 Corinthians only after distinguishing initial sign, private prayer, and public gift.
