Judgement Begins With the House of God

1 John 3:10-15 

10 In this the children of God and the children of the devil are manifest: Whoever does not practice righteousness is not of God, nor is he who does not love his brother. 11 For this is the message that you heard from the beginning, that we should love one another, 12 not as Cain who was of the wicked one and murdered his brother. And why did he murder him? Because his works were evil and his brother's righteous.
13 Do not marvel, my brethren, if the world hates you. 14 We know that we have passed from death to life, because we love the brethren. He who does not love his brother abides in death. 15 Whoever hates his brother is a murderer, and you know that no murderer has eternal life abiding in him.

We are told how to know the differences between those of God in Christ and those who are not His.  This is not speaking of those who say they are of Christ and those who deny Him, but of those among all who say they are Christ’s while some are not.  These are tests of true conversion, of knowing by the fruit or lack of it (Matthew 7:20, 12:33, Luke 6:43-44), which is a very unpopular thing to do - as if we are judging to condemnation instead of discerning in that sense of the word.  God wrote these words to follow, not just assent to their truth.  God judges the eternal fate by condemnation; we judge with discernment of those within who demonstrate or deny Christ and so teach to mislead or harm.  The tests here are lives changed to pursue righteousness, and to love others.  The example of Cain hating and murdering Abel has shown hate to be abhorrent to God and should be to us, for even Jesus made it clear that if we hate (do not love), we are murderers (Leviticus 19:17).  This is repeated here in verse 15.  Cain murdered out of hate and evil intent driven by jealousy, hating what was good in God’s eyes and wanting his own self serving recognition and reward.  If we so hate others, we are no better than Cain.  Therefore the world which is set against God hates us, of which we are no longer a part of if we truly are changed in Christ.  We died to our old sinful and hate ridden selves, and are alive in His love and forgiveness, and so we should reflect His life in us by pursuing holiness and loving others, not living in sin nor hating as we once did.  For if we continue to hate without remorse or repentance, we remain dead to God and not alive in Christ.  Loving our brother demonstrates the inner change of regeneration; such murderers of the heart do not have that eternal life.