A discourse on Jesus' command to "be perfect" from Matthew 5:48.
In a legalistic point of view, we reduce the demands of God's law to that which is doable. Or worse yet, through open cynicism or self-blinded naïveté, we reduce the demand to that which we ourselves have been doing. The standard becomes, "Be like me". Instead of God's standard becoming so high that it cost him his Son, it becomes so low that you only have to mimic the rites and morality of your local fundamentalist. In contrast, I believe that if you believe God really expects us to be perfect, you have no place to run but to the Cross. In contrast, your enemies' complaints engender apology and acts of reconciliation, not exasperation. That is the point of the comic.
Others have chimed in similarly. Tullian Tchividjian wrote,
"In Matthew 5-7, Jesus wants us to see that regardless of how well we think we’re doing or how much better we’re becoming, when “You therefore must be perfect, as your heavenly Father is perfect” becomes the requirement and not “look how much I’ve grown over the years”, we begin to realize that we don’t have a leg to lean on when it comes to answering the question, “How can I stand righteous before God”? Our transformation, our purity, our growth in godliness, our moral advances and spiritual successes–Spirit-animated as it all may be–simply falls short of the sinlessness God demands. And since a “not guilty verdict” depends on sinlessness, assurance is ultimately contingent on perfection, not progress."