I see two opinions of this floating around.
Me PERSONALLY I believe the sheep and goats judgment occurs at the second coming, not after the millenium.
I base this opinion on Matthew 25:31 which says that when Jesus comes in glory with angels. Therefore I believe it cannot be the great white throne, because where would Jesus be "coming from" with the angels if He is already on the earth during the millennium?
You see my point?
If you disagree with me, prove your point from Scripture! And lets discuss it!
The saints do not get judged at the great white throne judgment, for they already have their glorified bodies, and eternal life before the millennial reign of Christ.
Then Jesus comes back with all the saints and fights the world, and defeats them, and Jesus and the saints rule for 1000 years over the people that God spared at the battle of Armageddon.
Blessed and holy is he that has part of the first resurrection, for the second resurrection has no hold on them, and all people that are caught up in the first resurrection is all saved, which is before the millennial reign of Christ.
All the rest of the people that were not caught up in the first resurrection, have to go to the second resurrection after the millennial reign of Christ, the great white throne judgment.
They are people who were hypocrites, and heard the word of God but did not abide by it in the truth, for they held unto the world while claiming Christ, or did not abide by the Old Testament, and their sins were not covered by the blood of animals, which Jesus said to the hypocrites once He shuts the door they cannot enter concerning the first resurrection, and they shall have their portion with the hypocrites, and not everyone that says Lord, Lord, will enter heaven, for they did not do the will of the Father, but were workers of iniquity.
And all the people that heard the word of God, and rejected it, and all the people that never heard the word of God.
The hypocrites, and those that rejected the word of God will not be able to make it.
The people that never heard the word of God, or not sufficiently, will be judged on their belief in a higher power, who loves people, for He provided food, and the means to make clothing, and shelter, so the world is without excuse, so they should love people, and by their conscience, and if anything was amiss to ask the higher power for forgiveness.
Which creation testifies there is a God who created all things, and of His attributes, which one of them is love, so the world is without excuse, and covers the 2 greatest laws that everyone can see, love God, and love people.
Which love works no ill towards their neighbor, therefore love is the fulfilling of the law.
At the great white throne judgement some people will be saved for they abided by the 2 greatest laws love God, and love people, and were sincere, and asked God to forgive them if anything was amiss, for they did not have the advantage not hearing the word of God.
The only people that have a chance at salvation at the great white throne judgment are people that did not hear the word of God, or not sufficiently with no fault of their own.
Everybody that was a hypocrite whether Old or New Testament, and those that rejected the word of God and had sufficient preaching of it, but rejected it, and did not want to check in to it, or did and then said they do not believe it, will not make it.