Be you therefore perfect, even as your Father who is in heaven is perfect.
All Commentaries on Matthew 5:48 Go To Matthew 5
Jerome
AD 420
Many measuring the commandments of God by their own weakness, not by the strength of the saints, hold these commands for impossible, and say that it is virtue enough not to hate our enemies; but to love them is a command beyond human nature to obey. But it must be understood that Christ enjoins not impossibilities but perfection. Such was the temper of David towards Saul and Absalom; the Martyr Stephen also prayed for his enemies while they stoned him, and Paul wished himself anathema for the sake of his persecutors.
For whoso keeps the commandments of God is thereby made the son of God; he then of whom he here speaks is not by nature His son, but by his own will.