18 Little children, let us not love [merely] in theory or in speech but in deed and in truth-in practice and in sincerity. (Read: 1 John 3:16-24).
17 Again John's penchant for providing practical "tests" of the validity of one's faith comes to the fore. How can we know whether we would sacrifice our life for a fellow believer? We can know by being compassionate toward such a one in his or her present need. If we are unable or unwilling to sacrifice material advantage for the sake of our fellow believers, we know that the love of God is not in us. What are the conditions for our involvement? If we are in a position to see with our own eyes someone's need (as, for example, the good Samaritan did, Lk 10:29-37) and can offer help, then we cannot do otherwise than act. To withhold help in such a situation is to shut off compassionate action and to deny the presence of God's love in our own heart.
18 Turning back to "little children", John admonishes with the tone of a spiritual father pleading for the heartfelt response of his children. Love requires more than idle talk or exalted theology. It demands simple acts, which anyone can see, in order to meet the needs of brothers and sisters in distress. Any expression of love that fails here is not only empty but blasphemous (cf. Jam 2:15-16; 1 Cor 13:1-3).
[NIV BIBLE COMMENTARY Volume 2: New Testament].
JESUS IS LORD.