The law used to demand that your neighbor be loved and allowed hatred against an enemy. Faith, rather, requires that enemies be cherished. It breaks the tendency we have to be peevish and urges us to bear life's difficulties calmly. Faith not only deters anger from turning into revenge but even softens it into love for the injurer. It is merely human to love those who love you, and it is common to cherish those who cherish you. Therefore Christ calls us into the life of heirs of God and to be models for the just and the unjust of the imitation of Christ. He distributes the sun and the rain through his coming in baptism and by the sacraments of the Spirit. Thus he has prepared for us the perfect life through this concord of public goodness, because we imitate our perfect Father in heaven.
-- St. Hilary of Poitiers (315-367):
On Matthew 4,27; SC 254:146-48