# But one brother brings a lawsuit against another brother—and this before unbelievers

"It is bad that brothers have such bad disputes with each other that they go to court; it is even worse that those courts are run by unbelievers"

# brother brings a lawsuit against another brother

Here "brother" means fellow Christian, including both men and women.

# brings a lawsuit

asks the civil court to judge the matter

# and this before unbelievers

"and the brothers have unbelieving judges make decisions for them" or "and unbelievers in the community see brothers disputing with one another"