1 How can anyone of you who has a dispute with another dare to have it judged before the unrighteous, and not before the saints? 2 Do you not know that the saints are to be judging the world?*The question, “Do you not know?” indicates that if the person addressed does not know, he should, and his ignorance is culpable. For Paul to write in this way, his addressees had to have had a reasonable opportunity of knowing, or it would be an unfair gambit on Paul's part. On such a topic the information should be available in God's written revelation, and I believe it is. Consider Psalm 149:5-9. “Let the saints exult in glory; let them sing for joy on their beds. Let the high praises of God be in their mouth, and a two-edged sword in their hand, to execute vengeance upon the nations, and punishments upon the peoples; to bind their kings with chains, and their nobles with fetters of iron; to execute upon them the written judgment. This honor is for all His saints.” Note that the saints are in their beds! So the activity that is described in the following verses must take place in the spiritual realm. I assume that the ‘kings’ and ‘nobles’ includes both men and fallen angels. It seems clear to me that the intent of the Text is that we be doing this right now, in this life. There is no lack of ‘written judgments’ to be imposed: Zechariah 5:2-4, against thieves and liars; Proverbs 20:10, against those who use diverse weights and measures; Isaiah 10:1-2, against those who make unjust laws; Romans 1:26-32, against homosexuals and a variety of others (note that verse 32 says that “those who practice such things are deserving of death”, ‘are’ not ‘were’—since Romans was written after Pentecost, within the Age of Grace and of the Church, this judgment still applies). God's moral character cannot change; Psalm 34:16 says: “The face of Jehovah is against those who do evil, to cut off the remembrance of them from the earth.” Presumably before wiping out the remembrance He will have to cut off the evil people themselves.
Returning to 1 Corinthians 6:2, the only difference between present and future tense for ‘judge’ is the accent, and since the earliest Greek manuscripts generally do not have accents, in them the verb is ambiguous as to tense. Most, but not all, later manuscripts accent the verb as future and every version that I have seen follows suit. But if Paul is thinking of Psalm 149, then the present tense is correct—in fact, the immediately following passive form of the verb is present tense. I take Paul's point to be: if we are supposed to be judging the world, how can we possibly ask the world to judge us? To do so is illogical. So if the world is to be judged by you, are you not competent to judge the smallest matters? 3 Do you not know that we will judge angels?[b] How much more the things of this life![c] 4 Therefore, if you have disputes about such matters, appoint those who are least esteemed in the congregation to judge![d] 5 I say this to your shame. Can it be that there is not a single wise man among you who would be competent to judge between a man and his brother? 6 Instead, brother goes to law against brother, and this before unbelievers! 7 Actually, the very fact that you have lawsuits among you already represents a defeat for you.[e] Why do you not rather accept wrong? Why not rather accept being cheated? 8 No, you yourselves do the wronging and cheating, and to brothers!