1. IV. Obedience to Christ's Example (3:1-3:24)
    1. B. Our Actions Show What Leader We Obey (3:7-3:15)
      1. ii. Sinfulness hates righteousness (3:12-3:15)

Calvin

3:12-3:13
Cain is an example of the hatred that reigns in the devil's children. He is also an example of the danger of a belief in works salvation. Such a belief leads to a false assessment of our standing. But the 'works' of brotherly love flow naturally from the love of God, and so must be evident in the lives of His children. Hatred has primacy in the impious. The righteous must endure patiently the unprovoked hatred of the world.
3:14
Love is a sure sign of our passage into new life. It is not a cause of that passage, but a necessary follow-on. Life always precedes love. Even our faith and confidence should steer clear of our works as signs, and remain firmly on Christ alone.
3:15
This is not exaggeration. When we hate somebody we wish for their end, whether we work toward it or not. As such, hatred is as abominable to God as the physical act of murder, for the difference is minimal. Man doesn't consider hatred so vile only because he focuses on the outward appearance. God, on the other hand, looks at the inward spirit. [Whereas we cannot safely judge another's spirit, we can and should look to our own, and cast it in the light of Christ's own judgement.]
 
 

Matthew Henry

3:12-3:13
Cain's envy should deter us from similar passions. It showed his lineage to be from the devil, since that is who he resembled in action. He had no restraint. "Sin, indulged, knows no bounds." So far was he gone, that he murdered for the sake of religion. Sin teaches us to hate what we ought rather to admire. Given the source of these actions, and that he is the current ruler of this world, it should come as no surprise to be ill-treated by that world.
3:14-3:15
Love is the mark of our justification. By nature we are like Cain, but the rebirth brings change. (Jn 3:36 - In believing in Christ, we have attained eternal life, non-believers having attained instead eternal wrath.) Since this love is a mark of our justification, it cannot be a limited love that has affection only for those of our denomination, or those of similar sentiments. Rather, it must consider all as neighbors and extend itself to them. All mankind must be considered because God made them - and God ensures that murderers (inclusive of hatred) will be punished. (Ge 9:6 - The murderer's punishment is assured because his victim is the image of God.) All mankind - including the fallen - have a redeemer available in Christ, by which God shows His love for them. (Jn 3:16 - He loved them enough to provide His Son as Savior.) What He so loves, we ought to love as well. That love will show itself in prayers and attempts to convert and save the unsaved. Our love extends to a different and greater degree to those of Christ's body - as reflections of God's love and grace both in them and in us. Hatred is a sign of our continued state of death. Hatred tends toward murder, and is considered such, spiritually. It will bottle up our compassion, and expose them to sorrow and death. It exposes its targets - by the characterizations it spreads - to persecution and death. So, as hatred equates with murder, it must come of a carnal mind, and this is death. (Ro 8:6 - the mind set on the flesh is death.) The real transition from temporal life to eternal life will be proved or disproved by the spiritual state of the person - love a proof; hatred a disproof. The washing of guilt must include in it the cleansing from sin itself. (1Co 6:11 - we used to be that way, but Christ's cleansing has changed us.)
 
 

Adam Clarke

3:12
As Cain was a murderer, and a son of the devil, so are all who join in war - either as its authors or its perpetrators, or its justifiers. The seed of wickedness induces the wicked to destroy the righteous, for it cannot tolerate the seed of righteousness therein.
3:13
Neither justice nor mercy can be expected from the enemies of God, only persecution.
3:14
Death and life are presented as two kingdoms, and ourselves as having moved from the one to the other. (Col 1:13 - we have been transferred into the kingdom of life.) Into the kingdom of life, death and hatred cannot enter. Ergo, the presence of brotherly love shows us to be in life, whereas hatred shows us still trapped in the land of death.
3:15
Hatred is of the same principle as murder, and may well lead to it. Life springs from God's presence, and God's presence will not be in the hateful heart. Whereas a murderer might repent, and escape the verdict of this verse, Adam somehow refuses the same possibility for the war-monger. [This is the limitless God?]
 
 

Barnes

3:12
Cain is a strong example of the lack of love. (Ge 4:4-8 - Cain's fall.) His acts were done under the devil's influence; under the influence of envy. Lack of love for our brothers often leads to crimes against our brothers. Love, by itself, would be sufficient to put an end to crime.
3:13
We ought not to be surprised by the world's hatred. It is the same issue of evil hating righteousness. (Jn 15:17-19 - we must love each other, since the world will hate us, as it hated Christ before us. Why? Because we are not part of it.)
3:14
Spiritually, we have passed into life from death, as evidence of which our love for each other can be held forth. (Jn 13:34-35 - This is the command of our chief, and the badge of our membership in His body.) Amongst ourselves, this is the means we have of recognizing the truth of each other. To be otherwise is to be unconverted - regardless of confessions to the contrary. Lack of evidence means lack of renewal.
3:15
While we are not to understand the same degree of guilt in hatred as in murder, the only real difference is that the one who has not acted has been restrained by laws and fear of punishment. Were the restraints removed, the act would follow. "Any man may well shudder at the remembrance of the secret sins of his own heart, and at the thought of what he WOULD have been but for the restraining grace of God. And how wonderful is that grace which, in the case of the true Christian, not only restrains and checks, but which effectually subdues all these feelings, and implants in their place the principles of love!"
 
 

Wycliffe

3:12-3:15
Cain is put forth as the antithesis of love for our brothers. Cain slew with violence. (Rev 5:6 - the Lamb - as though slain with violence, Rev 5:9, Rev 5:12 - and thereby worthy. Rev 6:4 - War sent to incite men to slay each other with violence. Rev 6:9 - Under the altar were those slain with violence because of their testimony for God. Rev 13:3 - the head of the beast as though slain with violence Rev 13:8 - the Lamb who was slain with violence. Rev 18:24 - the prophets and saints were slain with violence.) We should cease to be surprised at our treatment in this life. Love is to life as hate is to death. Our being hated by the world is not the test, but rather, our love for the brethren. From God's perspective, the heart capable of murder is guilty of its commission. (Mt 5:21-22 - even derision brings guilt, for the derisive one is capable of becoming the murderous one, but for the grace of God.)
 
 

Jamieson, Fausset & Brown

3:12
Cain's wicked acts marked him as being the devil's. Envy led to hatred led to murder. Such has always been the state between the seed of woman and the seed of the serpent.
3:13
What would be truly surprising is if the world did love us! For "the world feels its bad works tacitly reproved by good works."
3:14
Our knowledge is an assured fact - our changed state (from death into life) - attested to by our love. (Col 1:13 - our state has changed from darkness to light. Jn 5:24 - believers pass from death into life.) This love is the basis for our knowing - not for the passage itself.; the evidence, not the cause. Some texts generalize whom we are to love by omission of 'his brother'. To not do so shows that we are still in death's grip, having had no saving change.
3:15
As with life and death, there is no middle ground between love and hatred. Having indulged the beginning of passions which tend toward murder, we stand guilty of the ends. Such as hate are even now walking in death.
 
 

New Thoughts

Father, forgive me. There are those I've nursed an anger toward. Help me to repent even now. Help me to hold to that repentance even in the temptations that fill each day. Teach me how to love in spite of their nature; to hold out hope for their conversion, rather than focussing on their present state. Let's face it: their state hasn't really concerned me one way or the other. It's my own pride and arrogance that need to be set aside. God, help me. Burn it away. Cleanse me. Change me. God, the message comes again and again. The prayer doesn't change in its essence. I need Your touch. I'll not be satisfied until I've known it; felt the change in myself that Your presence must surely bring. This current condition doesn't cut it, Lord. I cannot continue as I am. I cast myself on Your mercy, I submit myself to Your will. Do what needs doing, Oh Lord, that I may know with the assured knowledge of attested truth that I am - and always will be - Yours and Yours alone.