Frok said:
After reading through the text I think Paul is trying to make a point to the Corinthians to not have one gift dominate over another. If everyone speaks in tongues but nobody prophecies then visitors will think your nuts. Tongue-speaking was somewhat "showy" and thus maybe more popular to focus on?
It's the opposite. Paul says that prophecy is greater than tongues (v5) because you can understand a prophecy, but in a church like Corinth where everyone speaks Greek, tongues is useless (v9). If your minister preached in Russian (who doesn't know Russian), it would be pretty amazing to everyone, but beyond that it wouldn't be helpful because nobody in your congregation understands Russian. Prophecy builds up the church, tongues doesn't necessarily (unless someone can interpret). Paul concludes:
19 Nevertheless, in church I would rather speak five words with my mind in order to instruct others, than ten thousand words in a tongue.As far as the OP, I was interested in the hypothetical unbeliever entering the church. He hears a prophesy (sermon today) where the secrets of his heart are disclosed, he's called to account, and is convicted. This makes him fall on his face and worship. It is the "typical" conversion. Yet churches today, in an attempt to be "seeker friendly" and not appear to be judgmental, remove these elements.