2:9. "But if ye have respect to persons, ye commit sin, and are convinced of the law as transgressors."
"If" is better translated as "Since"
due to the Greek construction of this conditional statement which indicates that this practice of showing favoritism was in fact taking place among James' readers.
Have respect of persons. This is partiality (favoritism) and the Greek verb indicates that their behavior was not occasional, but a continual practice.
Convinced of the law. Since God's law (Deuteronomy 1:17
) forbids showing partiality, they were shown to be sinning by their practice of partiality.
Pastor Jack Howell
"Some bring God's curse on them by marking off part of the Bible, calling it erroneous, uninspired, less than the very Word of God."
- Dr. John R. Rice
"For I am not ashamed of the gospel of Christ: for it is the power of God to salvation to every one that believes; to the Jew first, and also to the Greek."
Proper Principles of Bible Study