13 So don't be surprised, friends, when the world hates you. This has been going on a long time.
14 The way we know we've been transferred from death to life is that we love our brothers and sisters. Anyone who doesn't love is as good as dead. 15 Anyone who hates a brother or sister is a murderer, and you know very well that eternal life and murder don't go together. 16 This is how we've come to understand and experience love: Christ sacrificed his life for us. This is why we ought to live sacrificially for our fellow believers, and not just be out for ourselves. 17 If you see some brother or sister in need and have the means to do something about it but turn a cold shoulder and do nothing, what happens to God's love? It disappears. And you made it disappear. 18 My dear children, let's not just talk about love; let's practice real love.
Matthew Henry's Commentary on 1 John 3:13-18
Commentary on 1 John 3:11-15
(Read 1 John 3:11-15)
We should love the Lord Jesus, value his love, and therefore love all our brethren in Christ. This love is the special fruit of our faith, and a certain sign of our being born again. But none who rightly know the heart of man, can wonder at the contempt and enmity of ungodly people against the children of God. We know that we are passed from death to life: we may know it by the evidences of our faith in Christ, of which love to our brethren is one. It is not zeal for a party in the common religion, or affection for those who are of the same name and sentiments with ourselves. The life of grace in the heart of a regenerate person, is the beginning and first principle of a life of glory, whereof they must be destitute who hate their brother in their hearts.
Commentary on 1 John 3:16-21
(Read 1 John 3:16-21)
Here is the condescension, the miracle, the mystery of Divine love, that God would redeem the church with his own blood. Surely we should love those whom God has loved, and so loved. The Holy Spirit, grieved at selfishness, will leave the selfish heart without comfort, and full of darkness and terror. By what can it be known that a man has a true sense of the love of Christ for perishing sinners, or that the love of God has been planted in his heart by the Holy Spirit, if the love of the world and its good overcomes the feelings of compassion to a perishing brother? Every instance of this selfishness must weaken the evidences of a man's conversion; when habitual and allowed, it must decide against him. If conscience condemn us in known sin, or the neglect of known duty, God does so too. Let conscience therefore be well-informed, be heard, and diligently attended to.