Christians (saints) will one day have a great responsibility to judge the world, and even angels.
It is expected therefore that there are people in church wise enough to judge the differences that arise between brothers in Christ, as they are, by comparison, small things. There is no reason for brethren to take their disputes to be resolved by unbelievers (the unjust, unfaithful, of less esteem in the church) in the courts.
Those who do so are already at fault, because they do not practise love to their neighbour and selflessness that are proper for a Christian: rather than suffering injustice and harm themselves they inflict injustice and harm to other brethren.
The unrighteous shall not inherit the kingdom of God. But Christians have been washed, sanctified and justified in the name of the Lord Jesus and by the Spirit of God.
Everything is lawful for a Christian (i.e., he has been is freed from the obligation to obey the law imposed on the people of Israel). But this freedom is limited by the following considerations:
The Christian no longer owns his own body, because:
He belongs to the Lord: he was bought at a price (the blood of Christ) so his body is ultimately the Lord's also. One day it will be transformed or resurrected, like Christ’s body was. He is a member of Christ: because he is a member of his church, which is the spiritual body of Christ. He participates in one spirit with Christ: the Holy Spirit dwelling in him. His body and spirit belong to God, and must glorify Him.
Therefore, the believer is not free to give his body to immorality (sexual activity outside of marriage): this is to sin against his own body.
1 Dare any of you, having a matter against another, go to law before the unrighteous, and not before the saints?
2 Do you not know that the saints will judge the world? And if the world will be judged by you, are you unworthy to judge the smallest matters?
3 Do you not know that we shall judge angels? How much more, things that pertain to this life?
4 If then you have judgments concerning things pertaining to this life, do you appoint those who are least esteemed by the church to judge?
5 I say this to your shame. Is it so, that there is not a wise man among you, not even one, who will be able to judge between his brethren?
6 But brother goes to law against brother, and that before unbelievers!
7 Now therefore, it is already an utter failure for you that you go to law against one another. Why do you not rather accept wrong? Why do you not rather let yourselves be cheated?
8 No, you yourselves do wrong and cheat, and you do these things to your brethren!
9 Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites,
10 nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God.
11 And such were some of you. But you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus and by the Spirit of our God.
12 All things are lawful for me, but all things are not helpful. All things are lawful for me, but I will not be brought under the power of any.
13 Foods for the stomach and the stomach for foods, but God will destroy both it and them. Now the body is not for sexual immorality but for the Lord, and the Lord for the body.
14 And God both raised up the Lord and will also raise us up by His power.
15 Do you not know that your bodies are members of Christ? Shall I then take the members of Christ and make them members of a harlot? Certainly not!
16 Or do you not know that he who is joined to a harlot is one body with her? For "THE TWO," He says, "SHALL BECOME ONE FLESH."
17 But he who is joined to the Lord is one spirit with Him.
18 Flee sexual immorality. Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body.
19 Or do you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own?
20 For you were bought at a price; therefore glorify God in your body and in your spirit, which are God's
1 Corinthians chapter 6