A: The Scriptural reference to the saints judging angels in heaven is in 1 Corinthians 6:
Does any one of you, when he has a case against his neighbor, dare to go to law before the unrighteous and not before the saints? Or do you not know that the saints will judge the world? If the world is judged by you, are you not competent to constitute the smallest law courts? Do you not know that we will judge angels? How much more matters of this life? So if you have law courts dealing with matters of this life, do you appoint them as judges who are of no account in the church? I say this to your shame. Is it so, that there is not among you one wise man who will be able to decide between his brethren, but brother goes to law with brother, and that before unbelievers? Actually, then, it is already a defeat for you, that you have lawsuits with one another. Why not rather be wronged? Why not rather be defrauded? (1 Corinthians 6:1-7, NASB)
To try and answer your specific question (which angels and for what will we be judging them?) we first need to understand the context of the passage.
Paul throws this comment into his reasoning against believers taking each other to court and is examining their current situation in light of their future glorified situation. For Paul (as well as the other New Testament writers – especially John), eternal life is not supposed to simply be a future reality but is to begin manifesting itself here and now in the believers life.
If you read the first 5 chapters of 1 Corinthians leading up to this passage, Paul is describing how the life of a Christian ought to look and lamenting at the sad state of the church in Corinth. As Paul turns his focus to the specific issue of lawsuits amongst believers, Paul is urging believers to not rely upon worldly authorities to settle disputes since they are members of the heavenly kingdom of God.
In the introductory verses of chapter 1, Paul says:
Now I exhort you, brethren, by the name of our Lord Jesus Christ, that you all agree and that there be no divisions among you, but that you be made complete in the same mind and in the same judgment. (1 Corinthians 1:10, NASB)
What a disgrace it seems to be in Paul’s eyes, that the brotherhood of believers be so divided that they are even suing each other before un-believing judges! Paul laments this very fact in 1 Corinthians 6:5-7 and says that it would be better for them to simply be defrauded then to hand matters of the church and believers into the hands and judgments of godless men.
In contrast to the bleakness of their current situation, Paul seeks to remind them of their identity in Christ and the reality that in the end it is the saints who will judge the world and angels, so how can they not judge amongst themselves in these petty matters?
There is much more that could be said on this passage … but the point is that Paul is referring to something that seems to be common knowledge or belief in the minds of the Corinthian believers, and is not developed any further in this particular passage. Paul’s comments are made in passing, which is what makes your question so difficult to answer: because the passage is silent on which angels and for what they will be judged!
It is possible that this comment is referring to the final judgment and that the saints will judge the fallen angels. The Scriptures refer to rebellious angels being held for judgment:
For if God did not spare angels when they sinned, but cast them into hell and committed them to pits of darkness, reserved for judgment; (2 Peter 2:4, NASB, emphasis added)
And angels who did not keep their own domain, but abandoned their proper abode, He has kept in eternal bonds under darkness for the judgment of the great day, (Jude 1:6, NASB, emphasis added)
However, it is difficult for me to ascribe judgment of these rebellious angels to the same type of activity to which Paul is drawing his comparison. The Final Judgment is something that is always described in the Scriptures as being done by God alone, not delegated to anyone else. Similarly, in the Final Judgment all matters will come into judgment – this is not settling a dispute or disagreement, this is judgment for the entire existence of the angelic beings!
What seems more likely to me is that this “judging” is referring to something that Jewish believers would have been familiar with and something that is revealed later in the New Testament (after 1 Corinthians was written) in the book of Revelation.
The Jewish believer would be familiar with the following concept of the future state of the righteous:
'Then the sovereignty, the dominion and the greatness of all the kingdoms under the whole heaven will be given to the people of the saints of the Highest One; His kingdom will be an everlasting kingdom, and all the dominions will serve and obey Him.' (Daniel 7:27, NASB)
In this revelation to Daniel, we see that God is restoring His authority and rule over all creation (something that was handed over to the Devil after the Fall in Genesis 3 – see Luke 4:5-8, especially verse 6; 1 John 5:19; and Revelation 12:5).
God’s activity in the nation of Israel is often helpful in illustrating God’s plan for His people of all times (Israel often serves as a type of what is to come, even if the fulfillment is imperfect prior to the final restoration of all things). We see God choose Abraham, make of him the nation of Israel, delivering them from Egypt with signs and wonders, then bringing them into the promised land and driving out the inhabitants before them.
God’s will was to call for Himself a people, and for Him to be their King (Deuteronomy 4:20) but the nation of Israel rejected God as their king and went the way of the world (Deuteronomy 17:4-5; 1 Samuel 8:4-9). Through this rebellion against God and rejection of His rule, God promises to bring a King who will rule forever through the line of David, and it is under this King that God will establish His everlasting kingdom (e.g. Isaiah 9:1-7; 11:1-10).
When God was King of His people (before they rejected his rule), God raised up Judges to rule His people (Moses through Samuel; see 2 Samuel 7:11 and 1 Chronicles 17:10). These Judges ruled in the authority of God with delegated authority from Him.
When God brings about the restoration of all things, He will once again be our God and we will be His people (Revelation 21:3). God originally created human beings (both male and female) in His image (Genesis 1:26-28) as the pinnacle of His creation. Part of this creation was the charge to rule over God’s creation. Although angels are certainly glorious beings, glorified human beings will be even more glorious!
When God rules among men and angels in the final state (the “Eschaton”), the saints will rule with God in a similar way that the judges ruled in the nation of Israel. However, this position of authority will be exercised in a place that is free from sin so the tragedies that are recorded all throughout the Scriptures will not continue.
To sum up: although 1 Corinthians 6:3 is not explicit as to what angels will be judged by the saints and for what they will be judged, it is my conclusion when looking at the Bible’s big picture that Paul is describing the reality that the saints have positions of authority in God’s kingdom above even the angels, yet in Corinth they can’t even get along! If a dispute were to arise between angels in heaven (which is unlikely!), the saints would be the ones to settle the matter … however, in Corinth these same saints cannot settle their own disputes and are raising cases against each other in the worldly courts before non-believers!
Paul’s main point is to live as the new creations we are in Christ, and to live in harmony and unity with one another, living lives that glorify our Lord and King, Jesus.