A simple review of a few of the texts which have this phrase will clearly show that the traditional way of thinking of it as a statement of pain and suffering will be unwarranted. Our language and idioms simply are not the same as the biblical ones. Case in point....
Job 16:9 - He teareth me in his wrath, who hateth me: he gnasheth upon me with his teeth; mine enemy sharpeneth his eyes upon me. (Obviously, the one doing the "gnashing of teeth" has great ANGER towards the other.)
Psalm 37:12 - The wicked plotteth against the just, and gnasheth upon him with his teeth. (Obviously, the wicked are ANGRY with the just and are "gnashing" their teeth at them.)
Lament 2:16 - ll thine enemies have opened their mouth against thee: they hiss and gnash the teeth: they say, We have swallowed her up: (Obviously, Israel's enemies are ANGRY and have attacked Israel. They are "gnashing" their teeth at Israel.)
Acts 7:54 - When they heard these things, they were cut to the heart, and they gnashed on him with their teeth. (Obviously, Stephen's accusers were ANGRY with Stephen and have attacked him. They are "gnashing" their teeth at him in ANGER.)
So from the hermeneutical principle that "scripture interprets scripture," we can see very clearly that when Jesus (Yeshua) say's:
"There shall be weeping and gnashing of teeth, when ye shall see Abraham, and Isaac, and Jacob, and all the prophets, in the kingdom of God, and you yourselves thrust out." Luke 13:28
He means on that day –
1) there will be many sad people 'weeping' at the realization that they have just lost the chance for immortality and will soon be put to death forever.
2) and there will be many very ANGRY people gnashing their teeth at God. It is they who will probably be cursing at God (i.e. gnashing their teeth) all the way to their last breath before being destroyed.
There is nothing more than "weeping and anger" that is being said in this ancient phrase "weeping and gnashing of teeth" which has been misinterpreted by tradition. The evangelical conditionalist position is biblically correct. Proper hermeneutics demands we compare scripture with scripture. This is a prime example of the help that comparison provides.