Speaking about relations within the Corinthian church, Paul is surprised by the custom of Corinthian Christians suing in secular courts and choosing arbitrators not from among themselves, but from outside. Apparently, Corinth in those days was not very different from Athens or other Greek cities, whose inhabitants very often sued one another for all kinds of reasons, so that court cases, including cases involving arbitrators, were common there. Meanwhile, in the Synagogue there existed a rule, at that time still unwritten, according to which all disputes between faithful Jews, and there were no others then, had to be resolved inside their own community, either with the participation of an arbitrator or in the court of the rabbinate.
For Paul, as a Jew, it was also strange to see that matters which could perfectly well be resolved within one's own community were being taken outside by its members, who brought in both official courts and arbitrators with no relation to the church. The matter also lay in the fact that a secular court, whether official or arbitral, treated cases involving violations of commandments given by God much more leniently.
It is no accident that the apostle reminds the recipients of his letter that sinners do not inherit the Kingdom, meaning that this remains true even when a secular court does not condemn a person for violating those commandments, as often happened in pagan courts. In those times, when the Judeo-Christian tradition was dominant in the Church, a church court would surely have considered the same cases on the basis of the norms of the Torah, and the verdict of such a court could have differed noticeably from the verdict of a secular court. But that was not the only issue.
The apostle says directly: why are you suing at all? Would it not be better to leave the matter as it is, if you consider one another brothers? Indeed, brothers can "insist on their rights" and sue one another only when, in essence, they have already stopped being brothers. And Paul points to the many lawsuits among members of the Corinthian church as an obvious sign of spiritual trouble in the church community: if everything in this respect had been normal in the church of Corinth, then lawsuits of this kind would either not have existed at all, or would have been very few, and all matters would have been resolved within the community.
