The first question was about how the rich treated the believers. This one is about how they treated Christ. Barnes says the "worthy name" is "doubtless, the name of the Saviour," and that those who persecuted Christians "would revile the name which they bore." James is asking his readers to weigh what they were doing. They were giving the best seats to people who spoke evil of the very name that made them who they were.

The readers would have to answer yes. James moves straight to what they should do instead: "If ye fulfil the royal law according to the scripture, Thou shalt love thy neighbour as thyself, ye do well" (James 2:8). He warns that showing favoritism means "ye commit sin, and are convinced of the law as transgressors" (James 2:9), and calls them to "so speak ye, and so do, as they that shall be judged by the law of liberty" (James 2:12).

The Greek behind "by the which ye are called" reads literally "the name having been called upon you." James calls it the "worthy" name, using kalos, good. Gill says it is the name "Of Christ, or Christians." Acts records that "the disciples were called Christians first in Antioch" (Acts 11:26). Gill reads "they" in two ways: unbelieving rich men who blasphemed the name of Christ, or rich professing Christians who, by dragging poor brethren before heathen courts, caused "the name of Christ, after which they were called Christians, to be blasphemed."

Believers carry a name that is not their own. It was "called upon" them, and it marks them as Christ's. That is why James treats favoritism as so serious. When the church honors those who mock Christ's name and pushes aside those who bear it, it sides with the wrong people.

This question also explains what follows. The cure James gives is not a new strategy for dealing with the rich but "the royal law" of love (James 2:8). People who bear the name of Christ show its worth by how they treat the poor neighbor in front of them.