1 John 3:15 - Joseph Benson’s Commentary on the Old and New Testaments

He, I have just said, who loveth not his brother, abideth in death; is void of the life of God: for whosoever hateth his brother And there is no medium between loving and hating him; is In God's account; a murderer Every degree of hatred being a degree of the same temper which moved Cain to murder his brother. And no murderer hath eternal life abiding in him But every loving believer hath. For love is the beginning of eternal life. It is the same in substance with future felicity and glory. The word ανθρωποκτονος, here rendered murderer, is by Macknight translated a manslayer, who, as he observes, differs from a murderer as manslaughter differs from murder: adding, “The hatred of one's brother may be the occasion, by accident, of putting him to death. For he who indulgeth hatred to his brother, lays himself open to the influence of such passions as may hurry him to slay his brother. So our Lord tells us, in his explication of the precept, Thou shalt not kill, Matthew 6:21. For he mentions causeless anger and provoking speeches as violations of that command, because they are often productive of murder.”