James 2:9
But if you show partiality, you commit sin and are convicted by the law as transgressors.

This verse is a second conditional clause answering the first conditional clause given in verse eight. There, James has said that “if you love your neighbour, according to the Scripture, you do well.” Here, he poses the contrary condition, pressing home the point he has been making since verse one: “But if you show partiality, you commit sin…” (Ei de prosōpolēmpteite, hamartian ergazesthe).

The Greek term translated “acts of favouritism” in verse one is the same as that translated “partiality” here, thus uniting the whole section. Just as favouritism is incompatible with faith in Jesus Christ, so it is also incompatible with the royal law of love which is the centre and sum of the whole law, and the most complete expression of the divine will. Whereas the one who loves their neighbour “does well,” the one who shows partiality is “committing sin.” It is worth noting that the verbs in the second conditional statement, like those in the first, are also in the present tense and so also imply enduring action. So Vlachos suggests that prosōpolēmpteite depicts a pattern of prejudicial behaviour (79). James names this bluntly for what it is: sin, a form of behaviour contrary to and in violation of God’s will as it is revealed in the Scripture.

Many commentators note that James need not journey far from the Levitical love command to find a specific prohibition against partiality; the two commands occur in the same passage:

You shall not render an unjust judgement; you shall not be partial to the poor or defer to the great: with justice you shall judge your neighbour (Leviticus 19:15).

To love one’s neighbour includes treating them with justice, and specifically, without partiality. To the degree that James’ hearers practice favouritism, they set themselves at variance with God’s expressed command: they “commit” sin. We have previously met ergazesthe in our discussions of 1:3 and 1:20, where it carries the sense of produces. The person is working and productive, but these are not the good works James will go on to commend, but an evil work springing from an evil heart (v. 4).

Not only is the partial person committing sin, they are also “convicted by the law as transgressors” (elegkomenoi hypo tou nomou hōs parabatai). The same law which is expressive of the divine will now acts as judge against those who violate its commandments. James again presses his primary point: in showing partiality, you are convicted; you have become transgressors of the law. Parabatai denotes a direct violation of a known command (Vlachos, 79), and as such constituted serious rebellion for the Jew and the Jewish Christian. Such a person was throwing off the divine yoke, and placing themselves instead under divine judgment (Davids, 116). McKnight (210) concludes, then, that acts of partiality in the congregation have a twofold effect, first releasing the destructive power and agency of sin to work in the midst of the congregation (cf. 1:14-15), and second, conferring the status of transgressors upon those who act in this way.