The Faithful Slave
Like the previous passage, this one can also be interpreted in at least two ways, depending on who you believe the 'evil slave' to be.
First, there is no question that the 'faithful and sensible slave' represents the 'faithful and sensible' Believer. For him, Christ is not just Lord in name, but Lord indeed, to whom he is accountable. To such will the Lord delegate greater authority over all His possessions in His Kingdom.
But the identity of the 'evil slave' is more problematic, primarily because of his outcome. The description of his destruction and torment is in line with Jesus' description of hell, the place where non-Believers will be kept for judgment. And herein is the problem. If the 'evil slave' is an unfaithful Believer, then Jesus is teaching that it is possible to lose your salvation. If the 'evil slave' is a non-Believer, then God holds all people accountable to Him as their Master, whether they believe in Him or not!
The bottom line is that all men and women will be judged when Jesus returns. He is a wise person who is found in 'faithful' service to Him, for the outcomes makes Faith the only 'sensible' choice!