Revised Standard Version reflects an emphasis in the Greek that is weaker in Good News Bible. The Greek is literally “brother against brother, and this before unbelievers.” “And this” could be translated as “and even more than that,” to bring out its full force. A similar phrase “and that even” is used at the end of verse 8. The phrase and that before unbelievers may be rendered as “and lets people who do not believe in Christ judge the case.”

Quoted with permission from Ellingworth, Paul and Hatton, Howard A. A Handbook on Paul’s First Letter to the Corinthians, 2nd edition. (UBS Handbook Series). New York: UBS, 1985/1994. For this and other handbooks for translators see here .