Our Lord Jesus Christ became incarnate and took on our nature to reveal himself to mankind as the model of all virtues, 'Learn from me,' he says to us, 'for I am meek and humble of heart.
Later, when he explains to the Apostles the mark by which they will be known as Christians, he does not say, 'Because you are humble.' He is purity most sublime, the immaculate Lamb. Nothing could stain his perfect, unspotted holiness . Yet he does not say, 'You will be known as my disciples because you are chaste and pure.'
He passed through this world completely detached from earthly goods. Though he is the Creator and Lord of the whole universe, he did not even have a place to lay his head. Nevertheless he does not say, 'They will know that you are mine because you are not attached to wealth.' Before setting out to preach the Gospel he spent forty days and forty nights in the desert keeping a strict fast. But, once again, he does not tell his disciples, 'Men will recognize you as God's servants because you are not gluttons or drunkards.'
No, the distinguishing mark of the apostles and of true Christians in every age is, as we have heard: 'By this', precisely by this, 'shall all men know that you are my disciples, if you have love for one another.'
(Friends of God, 224)
 cf John 8:46