Adam Clarke on 1 Corinthians 6:1

Dare any of you, etc. - From the many things that are here reprehended by the apostle, we learn that the Christian Church at Corinth was in a state of great imperfection, notwithstanding there were very many eminent characters among them. Divided as they were among themselves, there was no one person who possessed any public authority to settle differences between man and man; therefore, as one party would not submit to the decisions of another, they were obliged to carry their contentions before heathen magistrates; and probably these very subjects of litigations arose out of their ecclesiastical divisions. The thing, and this issue of it, the apostle strongly reprehends.

Before the unjust, and not before the saints? - The heathen judges were termed δικασται from their presumed righteousness in the administration of justice; here the apostle, by a paronomasia, calls them αδικοι, unrighteous persons; and it is very likely that at Corinth, where such corruption of manners reigned, there was a great perversion of public justice; and it is not to be supposed that matters relative to the Christians were fairly decided. The Christians the apostle terms ἁγιοι saints, which they were all by profession; and doubtless many were so in spirit and in truth.