CLAIM: The manager of a rich man’s estate makes friends by cutting their debts to his boss. It seems odd that Jesus would affirm the deceit of the unrighteous steward. Does Jesus praise lying and stealing from your boss?
RESPONSE: There are two major ways of resolving this difficulty.
OPTION #1: The shrewd steward was stopping the rich man’s greedy interest
Under this view, the “shrewd steward” was not acting immorally. Instead, he was simply cutting the dishonest interest or usury of his rich boss. The OT law prohibited such usury (Ex. 22:25; Lev. 25:35-37; Deut. 15:7-8; 23:19-20). So under this view, the steward was merely removing the interest. But there are a couple of problems with this view:
First, why are the interest rates different for each debtor? In the first example, the debt is cut in half (v.6). In the second case, it is cut by 20% (v.7). If he was getting rid of usury, why would it be different in each case?
Second, Jesus calls this steward “unrighteous.” Why would Jesus call him an “unrighteous manager” if he was protecting people from usury?
OPTION #2: The shrewd steward was acting immorally, but Jesus is making an a fortiori argument
The traditional view is that Jesus was using this parable to make a single point—namely, be shrewd with your resources while there’s still time. “Shrewd” (phronimos) means “to give sustained thought to something think of, be intent on, be careful/concerned about” (BDAG).
Parables typically only make one main point. Leifeld writes, “[It] is not that a manager is commended for an act of dishonesty but that a dishonest manager is commended for an act of prudence.”
This shouldn’t surprise us to see Jesus using immoral examples to make a point about righteous living. This is a case of an a fortiori argument. In Luke 11, he said, “If you then, being evil, know how to give good gifts to your children, how much more will your heavenly Father give the Holy Spirit to those who ask Him?” (Lk. 11:13) Later in Luke 18, Jesus compares the negative example of an unjust judge to how our loving God will answer prayer. In both cases, he argues: “If A, how much more B?”
 Leifeld, W. L. (1984). Luke. In F. E. Gaebelein (Ed.), The Expositor’s Bible Commentary, Volume 8: Matthew, Mark, Luke (F. E. Gaebelein, Ed.) (988). Grand Rapids, MI: Zondervan Publishing House.