Paul’s statement in Romans 6:23 correlates to what Jesus taught in Matthew 25:41&46 when he said,
41 Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels:
46 And these shall go away into everlasting punishment: but the righteous into life eternal.
Those who were judged and condemned to everlasting punishment, were judged according to their works(deeds, actions) and were recompensed accordingly by the justice of God.
In the book of Revelation, the results are very black and white, just as Jesus’ statement in Matthew 25:46 makes this clear. This is because in the final reality there are only those who follow the Lamb, and those who follow the beast. There are only the righteous and the wicked. There are only those whose sins are paid for, and those who pay for their own sins. Those who pay for their own sins will need all eternity because they can never repay their debt to God. Glory be to Him who has redeemed us with His own blood!