On the Mount of Olives Jesus is concluding His discourse to His disciples about His future coming in judgment, not just upon the unbelieving Jews, but upon all nations. For as was already happening in the Jewish nation, the truth of His words that will never pass away would sift the heart of all souls either as sheep who support the nature of His kingdom, or as goats who love the world and the nature of its kingdoms. The King in the parable, who represents Jesus, has just spoken His final words to the goats. With what words does Jesus now end the parable, and the Olivet discourse? See Mat 25:46. What does Jesus mean by eternal punishment? Some have argued that the root meaning of the Greek word for eternal (aionios) is an age or eon (aion), as if all that is meant is a very long period of time. How does the juxtaposition of eternal life with eternal punishment argue against this proposal? Think: if the punishment of the goats is not really eternal, should we expect that the life of the sheep is either? Notice also that aionios means without beginning, without end, or both. It communicates our understanding of forever, and is translated each of the 69 times it is used in the New Testament in this sense. In the LXX, it is frequently translated as everlasting or perpetual, and is the word used to describe the LORD as the Everlasting God (Gen 21:33). It is also used specifically to contrast with things that are temporal (2Co 4:18, 5:1). Even aion, which can mean an age in the sense of a long period of time (cf. Mat 13:39-40, Luk 20:34-35), is used even more frequently to communicate the sense of forever, often by referring to an age of ages, or ages of ages (translated forever and ever; cf. Eph 3:21, 1Pe 5:11, Rev 4:9-10, 14:11), but also not infrequently directly by the word itself (cf. Luk 1:33,55, Joh 6:51,58, etc…). If Jesus had meant to communicate that the punishment He speaks of would in fact end at some time, He could not have used a more inappropriate word. While grace is extended to men in this life in order that all may be saved, what does eternal in Mat 25:46 communicate about the eventual unalterable state of every soul? Cf. Luk 16:26 and note.
What does Jesus mean by eternal punishment? Some have argued that a root meaning of the Greek word used for punishment is to prune and so Jesus is referring to an age-long process of pruning that will eventually lead to the goats’ salvation. Notice though that the Greek word used for punishment (kolasis) and its verbal form (koladzo) are found over 40 times in Biblical usage but never with the meaning of prune. Without exception the words are translated in the sense of punishment or vengeance, and often in the sense of severe punishments like torture. See 3Macc 7:3, 4Macc 8:9, Wis 19:4; cf. also the other NT uses in Act 4:21, 2Pe 2:9, 1Jo 4:18, as well as Mat 18:34. Consider too: even if the word was used for its remote connection to pruning, would that necessarily imply the goats’ eventual salvation, or that they are cut off from God and cast into the fire in order that the sheep who are connected to Christ as branches of His vine may bear a fullness of fruit for His kingdom and experience the fullness of that for which they are saved? Cf. Joh 15:2,6.
It is significant to note that kolasis was the word used in Eze 14:3-4,7, 18:30, and 44:12 in the LXX to translate as punishment of iniquity the Hebrew word we find in English as stumbling block of iniquity. The implication is that sin causes one to stumble, and the bruising fall that results is the consequences, so that one is punished by the very things by which he sins and is caused to stumble (cf. Wis 11:16). Those who harden their hearts to persist in sin stumble further and further from the light of God, and fall harder and harder in their deepening darkness. Such punishment of their sins by their sins becomes eternal when their own hardness of heart prevents them from ever turning back in repentance. Like the Pharisees who set forth their evil as good and called good evil in accusing Jesus of casting out demons by the ruler of demons, they reach a point in their hardness and darkness that their sins can no longer be forgiven because they can no longer be repented of. At that point, all they can do is go away into the eternal punishment they chose for themselves as the natural consequence of their sins—an endless stumbling deeper and deeper into a bottomless pit of darkness, to suffer and be consumed by the same eternal fire as the devil and his angels. In what way was the hardening of Pharaoh’s heart to progressively greater judgments that devastated Egypt and culminated in the utter destruction of him and his army a temporal picture of this eternal reality? What does this again remind us about the sinfulness of sin, why it is so evil and every sin consequential, and why God’s commandments are given for our protection to prevent us from ever starting down that path to perdition? See Deut 10:12-13, Psa 119:165, Isa 48:17-18, Jer 6:16, 7:23, 1Jo5:3; cf. 1Ti 6:11, 2Ti 2:22.
Considering the eternal nature of those created in the image of God and their potential to fall to ever-greater depths of sin and suffer the ever-greater torments that must accompany such sin, is it possible that the eternal fire prepared for the devil and his angels is actually a mercy from God to the wicked, and the lake of fire is like the sea in containing their evil within bounds so as to prevent an unending increase to their sufferings? Cf. Job 38:8-11, Isa 57:20-21, Jer 5:22.
 The punishment of the wicked in the future state will be an everlasting punishment, for that state is an unalterable state. It can neither be thought that sinners should change their own natures, nor that God should give his grace to change them, when in this world the day of grace was misspent, the Spirit of grace resisted, and the means of grace abused and baffled. Matthew Henry.
 3 Maccabees 7:3 Certain of our friends, frequently urging us with malicious intent, persuaded us to gather together the Jews of the kingdom in a body and to punish them with barbarous penalties as traitors.
 4 Maccabees 8:9 But if by disobedience you rouse my anger, you will compel me to destroy each and every one of you with dreadful punishments through tortures.
 Wisdom 19:4 For the fate they deserved drew them on to this end, and made them forget what had happened, in order that they might fill up the punishment that their torments still lacked. (Speaking of the drowning of Pharaoh’s army in the Red Sea after all the other plagues that had befallen the Egyptians.)
 Wisdom 11:16 …so that they might learn that one is punished by the very things by which one sins.