Wailing and Gnashing of Teeth

I have always imagined that when the Bible described the "wailing and gnashing of teeth" of those cast away from the presence of God in the judgment that this was an expression of physical pain, sort of like when a linebacker pulls a hamstring (cf. Matt. 13:42, 50). But I was stunned to find the same word for "gnashing" used in Acts 7:54. The scene is the martyrdom of Stephen. The word of God says that after his testimony that "when they heard these things they were cut to the heart, and they gnashed at him with their teeth."

The context here is that they utterly despised Stephen and were enraged at the words which he spoke; his words were words of condemnation to them. I wonder now if that wailing and gnashing signifies something more than more pain at the torment they are enduring. I believe that it also signifies their continuing hatred of God, especially because they have been righteously judged for their sins.

It is incredible to imagine that after seeing the glory of God in Christ, and even after hearing a just and holy verdict, that those who are sentenced will feel, instead of remorse, even greater hate towards God. But I believe that this is entirely possible, and I believe that apart from the grace of God, such enmity is the natural response of the fallen heart. This makes the miracle of the newbirth and the staggering change that it brings in the human character all the more marvelous.

What say you? Do you believe that when the wicked are judged that they will be repentant, or that they will become even more recalcitrant than before? Will the gnashing of teeth be out of pain only, or will they gnash their teeth at the Sovereign God the way they did at His martyr Stephen?