21 ¶ [Of course verse 16 is a direct reference to Jesus Christ as the promised "rest" and foundation stone they rejected.
In the Olivet discourse Luke cites the words "trodden down" by the gentiles which has reference to A.D. 70 destruction by Titus and the Roman Armies.
As I have posted several times this is what I believe Paul was referring to...
Paul seems to contradict himself in this passage. First he says that tongues are a "sign" for unbelievers, but then he says that if unbelievers see people speaking in tongues, the unbelievers will think that the believers are out of their minds.
It turns out that "uninterpreted tongues" have been used in Israel's history as a sign to the unbelieving Israelites that God's judgment had come upon them. Paul was quoting a prophecy from Isaiah 28:11-12:
"Very well then, with foreign lips and strange tongues God will speak to this people, to whom he said, "This is the resting place, let the weary rest"; and, "This is the place of repose"-- but they would not listen." (Isaiah 28:11-12)
This prophecy was fulfilled when the Assyrian army swooped down upon Israel speaking a foreign language (an uninterpreted tongue), carrying Israel off into captivity. Paul used an example from Israel's history to show that uninterpreted tongues are sometimes used as a "sign" for unbelievers that judgment has come upon them.
Then Paul pointed out that if an unbeliever enters a church where Christians seem to have lost their minds, the unbeliever wouldn't see this as a sign of impending judgment. This is why Paul said that prophecy is much more beneficial during a church service.