If someone is a perfectionist, it suggests that they are a taskmaster and demand everything to be precisely right, down to the last detail. However, when Jesus says, “Be perfect, as your heavenly Father is perfect,” he does not ask for detailed perfectionism. In Luke’s gospel, the companion passage is almost identical to today’s passage from Matthew, except that instead of perfect, Luke has “merciful”: “Be merciful as your heavenly Father is merciful.” Therefore, Luke has interpreted what Jesus meant by “being perfect.”
Being perfect means to love others unconditionally. It involves loving others in the same way God loves us. This is the central message of Jesus' teachings in the Sermon on the Mount - to love one another with a selfless love that seeks nothing in return.
Jesus urges us to love in the same way that God loves, which indicates that this command is not impossible to fulfill. Though we may not be capable of loving in this divine manner independently, we can accomplish it with the help of God. As Jesus later tells his disciples in Matthew's gospel, "For God, all things are possible."