If we are honest with ourselves, we would all have to admit some prejudice in the way we look at people. It may not be based on race, but we all have something (or things) that either draw us to a person or push us away. It happens in churches, too. The person of wealth may get special treatment. The person who has been a member for decades may have more of a voice in things than a newcomer does. Prejudice can take on many forms.
In James' letter, he warned Christians to be careful and not let any prejudice into their gatherings. The church then, as it is now, was a mixture of people from very diverse backgrounds. Their were rich Christians and poor Christians. James told them to treat everyone as a child of God--to honor the poor, just as Jesus said they would be honored by God. We all have a judgement coming, he said, and God will show mercy to those who show mercy.