If there is no love, other blessings profit us nothing. Love is the mark of the Lord’s disciples, it stamps the servants of God, by it we recognize his apostles. Christ said: “This is how all will know you for my disciples.” By what? Tell me. Was it by raising the dead or by cleansing lepers or by driving out demons? No. Christ passed over all these signs and wonders when he said: “This is how all will know you for my disciples: your love for one another.”
For the power to perform those other wonders is a gift which comes only through a grace from on high. This gift of love must also be achieved through man’s own earnestness and zeal. A man’s nobility does not usually stamp the gifts which are given from above in the same way as it marks the achievements which come from a man’s own efforts. Therefore, Christ said that his disciples are recognized not by miracles but by love. For when love is present, the one who possesses it lacks no portion of wisdom but has the fullness of complete and perfect virtue. In the same way, when love is not there, man is bereft of every blessing. This is why Paul exalts love and lifts it on high in what he writes. Still, for all he may say about love, he never fully explains its true worth.
(St. John Chrysostom, On the Incomprehensible Nature of God, pp. 52-53)