James 2: 1-13 appears to be an admonition primarily against showing partiality to the rich in any given church. Is there also an underlying principle implied not to show partiality or favoritism in any way, shape or form towards anyone in the Body for any reason (not just the wealthy)?
I think the Bible tells us that God loves all believers equally. James used the rich man as an example because the rich are often more easily identifiable by their appearance, and right or wrong, appearances count with us. As James pointed out, those of ordinary means often defer to the wealthy, not taking into consideration that a wealthy person may have gotten that way at the expense of the poor.
But rich or poor, attractive or plain, impressive or ordinary, all believers are God’s children and as such are loved unconditionally. This is why James was admonishing us to avoid showing favoritism to anyone for any reason.