James 2:11

‘For he who said, “Do not commit adultery”, said also, “Do not murder”. Now if you do not commit adultery, but do murder, you are become a transgressor of the law.'

He then illustrates this from two basic laws, the law against adultery (the breaking up of a marriage relationship and the stealing of a man's wife), and the law against murder (the stealing away from a man of his life by death, and of someone's beloved relation by the ending of the life of that relation. Everyone murdered is someone's son or daughter). The laws were carefully selected. No one would have denied that in these cases any guilty party, at least theoretically, deserved death. In the ancient Law these two crimes carried the death penalty. They were seen as the most serious crimes of all. But James' point is that it is equally as heinous in God's eyes to act in a way that reveals that we do not love our neighbours as ourselves in lesser thing, as it is to reveal that lack of love by murder or commit adultery. And we should note in this regard that Jesus had made clear in the parable of the Good Samaritan that our neighbours were men of all races. Thus our love is to be shown towards all, and especially towards those of good will like the Good Samaritan, and to fall short of this requirement is to be as bad as an adulterer or a murderer.