Instead, does a Christian sue a Christian, and do this before unbelievers?

From Paul, called to be an apostle of Christ Jesus by the will of God, and Sosthenes, our brother,

So by your knowledge the weak brother or sister, for whom Christ died, is destroyed.

But now I am writing to you not to associate with anyone who calls himself a Christian who is sexually immoral, or greedy, or an idolater, or verbally abusive, or a drunkard, or a swindler. Do not even eat with such a person.

To the rest I say – I, not the Lord – if a brother has a wife who is not a believer and she is happy to live with him, he should not divorce her.

But if the unbeliever wants a divorce, let it take place. In these circumstances the brother or sister is not bound. God has called you in peace.