I will add only one additional thought to Mike's fine answer, above, particularly regarding his singling out "teachers/preachers/priests" as the primary "target" of Jesus' teaching on stewardship.
Jesus was speaking, of course, to His followers. Peter in fact asked his Lord if he was speaking to him and his fellow disciples or to "everyone else instead" (v.41). Jesus' response to Peter was,
"'Who then is the faithful and sensible steward, whom his master will put in charge of his servants, to give them their rations at the proper time?'" (v.42).
In other words, Jesus' words were primarily directed to stewards, or true believers, and not to unbelievers. Jesus' point is that His true followers are stewards of everything entrusted to them. Today, for example, not all believers have public spiritual gifts such as pastor, priest, teacher, leader, bishop, elder, deacon, and so on. Each of us has, however, been entrusted by God with a gift (or spiritual gift mix, as Christian writer C. Peter Wagner puts it).
The clear teaching of Scripture in this regard is summed up as follows:
"For who regards you as superior? What do you have that you did not receive? And if you did receive it, why do you boast as if you had not received it?" (1 Corinthians 4:7 NAS).
Put differently, whatever gift(s) we've been given, they are just that: gifts, given to us by God. In the crassest of terms, perhaps, God has made an investment in all His children who believe in His Son, and He expects a return on His investment, much like the master of slaves who went on a journey. Before he went, however, he entrusted one, two, and five talents, respectively, to each of three of his slaves, *according to their ability.
In today's money, one talent would be about $360k, with two talents worth $720k, and five talents $1.8M. The master's expectation was for each slave to invest his respective number of talents so that when the master returned, the talents would have earned more talents.
Likewise as Christ's bondslaves, if God has given us the gift of helps, for example, then we are to function within the body of Christ as cheerful helpers and servers. If we have the gift of giving, we're be faithful, generous, and inconspicuous givers (see Matthew 6:1-4). If our enduement is encouragement, we're to encourage those who need encouragement. And the same goes for the leader, the pastor-teacher, the prophet, the person with discernment, the administrator, those who show mercy, and so on.
In conclusion, Jesus in His teaching in Luke 12 was not targeting just "teachers/preachers/priests," but He was addressing as well each and every believer. Since each of us has been given a function within the body of Christ, God expects us to function in our area(s) of giftedness as faithful stewards of God's good gifts. As Paul concluded in his letter to the Roman Christians,
"Since we have gifts that differ according to the grace given to us, each of us is to exercise them accordingly, according to the proportion of his faith" (12:6 NASBUE).
And to the Corinthian believers he said,
". . . moreover, it is required of stewards that [they] be found trustworthy" (1 Corinthians 4:2 NASB).
The concept of differing degrees of punishment touches on a subject which appears throughout the New Testament. Since Jesus in Luke 12 was addressing believers, the punishment of which He speaks is not eternal damnation in hell; rather, it is akin to the loss of rewards at the Judgment Seat of Christ.
"For we must all appear before the judgment seat of Christ [, the bema], so that each one may be recompensed for his deeds in the body, according to what he has done, whether good or bad" (2 Corinthians 5:10).
In Paul's first Corinthian letter, he puts it this way:
". . . each man's work will become evident; for the day [of Christ's judgment at the Bema] will show it because it is to be revealed with fire, and the fire itself will test the quality of each man's work. If any man's work . . . remains, he will receive a reward. If any man's work is burned up, he will suffer loss; but he himself will be saved, yet so as through fire" (3:13-16 NASB, my emphasis).
Potentially, at least, the most difficult verse in Jesus' teaching here is verse 46, where we read
". . . the master of that slave [i.e., the wicked slave who says to himself "My master is delayed"] will come on a day when he does not expect him and at an hour he does not foresee, and will cut him in two, and assign him a place with the unfaithful" (NET Bible).
If the NET Bible is correct, the word unfaithful can be linked to the notion of faithfulness, which appears earlier in Jesus' teaching. In other words, each "bad" and unfaithful slave will be assigned a place with all the other bad and unfaithful slaves who did not truly believe the master when he said "I'll be back!" (a la Schwartzenegger's Terminator).
Even so, there can be unbelievers among believers, yes? Not unbelievers who fail to believe IN Jesus, but believers who fail to BELIEVE Jesus when He says "I'll be back, so be faithful!" These unfaithful ones could also be called carnal, or fleshly, Christians (see 1 Corinthians 3:3). Yes, the punishment sounds severe (the NET says "cut . . . in two"; dicotomew in Greek), and it is. Along with the other punishments, however, it is simply the most severe of the three (viz., few stripes, many stripes, being cut in two).
As for the notion of instant sanctification at the time of death (or resurrection), this passage does not teach that, I believe. Our sanctification may cease when we die, but we Christians still have to face the Judgment Seat of Christ, where our works will be put through the fire (and we'll be saved, "yet so by fire")
While the Bema is not a judgment of punishment but, rather, a judgment of rewards or lack thereof, the loss of rewards is similar to punishment, though from one point of view that punishment is self-inflicted, as it were, since unfaithfulness is a choice we all can make throughout our lives here on earth. Wood, hay, and stubble, or gold, silver, and precious stones: the choice is ours!