The point of this parable is not that the Lord’s return is doubtful or completely unexpected (see Matthew 24:45–51; 25:1–30; Luke 12:36–38; 19:12–27). Rather, it teaches that there will be no warning sign before he comes. The parable uses symbolic language in at least two ways:
The master (Greek kurios, “lord” or “master”) represents the Lord Jesus Christ.
The servants represent the Christian community.
However, interpreting the doorkeeper as the apostles or Peter developed later, after the New Testament period.
at midnight, when the rooster crows, or in the morning: These four times match the Roman division of the night into four watches of about three hours each. They simply mean that the master may return at any time during the night.