As has already been said, James speaks here especially about love. He says that he who transgresses it becomes a transgressor of all the commandments, because love is the all-embracing headship of all the commandments.
If one were to say that whoever transgresses any commandment becomes a transgressor of all the other commandments, then no man could be saved. Each person would have to be perfect and without any lack in all the commandments.
Yet we often see that one who firmly remains in purity and chastity is sometimes overcome by anger. One who gives alms often has envy.
From this it is clear that the brother of the Lord is not speaking here about the transgression of every commandment, but specifically about love.
One must not labor at the practice of the commandments in a defective way, that is, with partiality, loving the rich man but not the poor man. Rather, this practice must be perfect, loving rich and poor equally.
Theophylact and Oecumenius interpret this saying in the same way. Basil the Great shows still more fully that if someone happens to transgress one of the commandments, he also transgresses all the other commandments.
The reason is that all the Lord's commandments are bound to one another like a chain woven of gold. He who loosens one loosens all the rest.
"For all of them, according to the soundly understood intention of Scripture, are so connected with one another that by the violation of one the others are necessarily violated" (Longer Rules, Introduction).
He continues: If ten talents are given to someone for safekeeping, and he keeps one or two talents for himself while paying back the rest, he is not considered honest for paying back the greater part. He is called unjust and covetous for squandering the smaller part.
Someone may have honored his father for ten years, but at the end strikes him only once. He is not honored as one who has done good, but is handed over to judgment as a parricide (ibid.).
What am I saying? The divinely revealed Father adds: why do I speak of squandering? Even the man entrusted with one talent was condemned, though he later returned in full and without deceit all he had received, because he added nothing to what was given (ibid.).
That all the commandments must be kept is confirmed by the Lord's words to the disciples: "Go therefore and teach all nations." He did not say to keep one thing and neglect another, but "teaching them to observe all that I have commanded you" (Mt 28:19-20).
The same Basil says, "If not everything were necessary for us to attain the goal of salvation, then not all the commandments would have been written. Nor would we have been commanded necessarily to keep them all.
"What profit is there for me in other merits, if by calling my brother a fool I shall be liable to Gehenna?" (ibid.).
Metrophanes of Smyrna holds the same opinion as Basil the Great. Interpreting this saying of the brother of the Lord, he says that all the commandments are like one body with different members.
When one member suffers, all the members suffer with it. So also, he who transgresses and rejects any one commandment rejects and transgresses all the other commandments together with it.
This is shown by the fact that if someone keeps all the other commandments well, but kills or commits adultery, he is not saved by keeping the rest. He is subjected to torment because of the transgression of one commandment.
Since he is subjected to torment, this clearly shows that he is subjected to it as a transgressor of the law.
If such a man is tormented for transgressing one commandment, how much more is one tormented who transgresses the wholly surpassing and all-embracing commandment of love?
I mean love for one's neighbor, in which love for God is contained and fulfilled. As blessed Paul said, "For the whole law is fulfilled in one word: You shall love your neighbor as yourself" (Gal 5:14).
And this is true. For he who loves his neighbor as himself does not desire to kill, commit adultery, steal, slander, swear falsely, bear false witness, or do anything else forbidden by the law. Rather, he desires to keep all the commandments.
He who keeps all the commandments undoubtedly loves God with all his heart, all his soul, and all his strength. This is the first commandment.
Do you see how he who keeps love for his neighbor keeps all the commandments? He who transgresses it transgresses them all.
By the impartial law of liberty he means the New Covenant, as was said above. Christians will be judged according to the New Covenant of the Gospel, as befits the free, not according to the Old Law, which is more fitting for slaves.
And just as the New Covenant in which Christians believe is free, as we said above on "he who looks into the perfect law" (Jas 1:25), so they too must be free and not slaves to passions and to men.
Paul says, "Do not become slaves of men" (1 Cor 7:23). And the Lord said, "Whoever commits sin is a slave of sin" (Jn 8:34).
THEOSIS