Today's meditation from Forward Day by Day is worth reading:
Matthew 5:38-48. Be perfect.
This is one of those sayings of Jesus that, on the face of it, seems incomprehensible. How can we possibly be perfect? Imperfect is surely what we most profoundly are. In fact, we are perhaps a shade too quick to affirm (under the guise of offended humility) the absolute impossibility of our own perfection.
Jesus himself knows our human frailty better than most, and he does not mock us.
So what can this possibly mean? Context is important. Jesus is speaking here of love of neighbor. He is not urging us to a kind of legalistic purity, but to whole-hearted love-rooted in our relationship with God our Father. This radical love knows no limits, extends beyond boundaries of family and nation, even to our enemies. Christian love is not a matter of deciding who is "worthy." We have been loved beyond any deserving; we are to love others the same way.
Perhaps this commandment is a promise as well. After all, St. Athanasius reminds us, "Christ became what we are that he might make us what he is." The more we live into God's love for us, the more we will be able to love with his love. "Be perfect," Jesus says, "as your heavenly father is perfect."