When Jesus warns farther along in Matt. 25:30 that those who are afraid to spend the talents, (measures of grace which have been given them for the building of God’s kingdom) will be “thrown into outer darkness, where there is weeping and gnashing of teeth,” that passage is generally interpreted by evangelicals as unbelieving sinners being thrown into hell, or the Lake of Fire (Rev. 19:19-20:3). Although this may well be an accurate aspect of its interpretation, may I suggest that there is a much more personal meaning to each of us as believers. As with the foolish virgins, the negative person in this parable is not a pagan (foreigner), but a “servant” of the king. Therefore, this passage deals with those who have experienced salvation from sin, but have refused to fulfill their calling for building God’s Kingdom by grace.
The outer darkness, therefore, in this context, is simply the place of losing the revelation of grace which one once had. It is the place of experiencing negative consequences which one doesn’t understand (no light of revelation), because one has failed to take the time to truly “know” the gracious, generous King. The servant whose talent is taken from him accuses the king of being an unfair “taker” of what is “not His.” (Mt. 25:24) So that is the judgment he receives.
The part about “gnashing of teeth” always sounded to me like someone in pain. But actually, throughout the rest of Scripture, this expression refers to angry, bitter accusation and attacking of others. (Acts 7:54 & Lam. 2:16, for example) Therefore, because Jesus said, “As you judge, so shall you be judged,” (Mt. 7:1-2) may I suggest that the “gnashing of teeth” here refers to the “wicked” servant:  being stuck with his own false view of harsh accusation against the king (i.e., his own “gnashing of teeth” against his king), by which he feels resentfully sorry for himself that the king was “so mean” to him; and  being attacked by the judgments of others, who falsely accuse this servant and “gnash their teeth” at him, just as he treated his king.
A victim mentality is the most deadly of all sins, because it leaves no room for humility that leads to repentance. It allows us to maintain an excuse for self-pity, failure, depression, and blaming others for our problems. It demands sympathy, manipulates pity where tough confrontation is what is really called for, and hides behind a wall of false “compassion,” wherever it finds a sympathetic ear. It slanders those with the discernment to see through its self-centeredness, and it likes to collect malcontents as its friends. It accuses of “harshness” or “hard-heartedness” those who see the truth.
But Jesus, who had more compassion upon desperate sinners, upon the weak, and the poor than anyone could fathom, had no tolerance for this imposter demon. His biggest miracles sometimes came from saying or doing things which sounded terribly unkind, but which exposed the true motives of those seeking healing, and which forced them to embrace humility over potential offense: For example, he called the Syro-Phoenician woman a “dog,” a common Jewish description of Gentiles (Mk. 7:24-30); He ignored two blind men who followed Him for a long way, begging Him to have mercy upon them (Mt. 9:27-30); He asked the lame man at the Pool of Siloam (Jn. 9:7-11) if he wanted to be healed, and then ignored the man’s excuse of not having anyone to carry him into the water on time. But in each case, the person had the desperation to put humility and cooperation over the temptation to get offended or to accuse Jesus of being “mean.” As a result, each received a miracle recorded for posterity, encouraging people, still, 2000 years later.
So ask yourself: Where have I been cast into the outer darkness of missing God’s grace, because I was more determined to accuse Him than to invest the grace He gave me? Eagerly receiving miracles or blessings by faith is not about “selfishness;” quite the contrary, rejecting or burying God’s grace is about the selfishness of being afraid to risk failure. It is about the selfishness of justifying our failure and blaming God for it, claiming it “just wasn’t His will to heal me.” It is time to abandon our distorted theologies which sound humble on the surface, but which are really fearful and lazy, accusing God of not being good and generous. (And lest you think I’m being rough, I write the lessons I am in the process of learning the hard way myself.)