First of all it is not a misunderstanding.
You have to know how the word dead is used, and it does not say just death and Hades gave up there dead. It first says that there was the dead small and great walking before the throne, and they were judged by works. These are all those that died after the first resurrection, and the millennial reign of Christ. During the battle of Armageddon. Then after it says about the dead small and great walking before the throne and the books being opened, then it says the sea gave up its dead, then death and Hades gave up their dead and they were judged by their works.
If you say there is no believers at the time of this judgment, then you are saying that nobody comes to believe in Christ during His millennial reign on earth. That is not the case, as the bible clearly says that there will be believers here at this time. The thing is it will not be us that is being mentioned here, because we who believe right now will have already be caught up by the first resurrection. This has to be referring to those who came to believe in Him after the first resurrection and during His millennial reign.
Plus, to further go back to what I was saying about understanding how dead is used. Look at this scripture;
1 Thessalonians 4:14-17
14 For if we believe that Jesus died and rose again, even so God will bring with Him those who sleep in Jesus.[a]
15 For this we say to you by the word of the Lord, that we who are alive andremain until the coming of the Lord will by no means precede those who are asleep. 16 For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. 17 Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord.