Understanding Revelation (14:2-3)

"And I heard a voice from heaven like the roar of many waters and like the sound of loud thunder. The voice I heard was like the sound of harpists playing on their harps and they were singing a new song before the throne and before the four living creatures and before the elders. No one could learn that song except the 144,000 who had been redeemed from the earth."

(Revelation 14:2-3)

The sound which John hears is that of a new song, which is a loud echo from a very prominent theme throughout the Old Testament in which the people of God sing songs of victory in jubilant celebration after deliverance from their enemies, as in Psalm 33, 40, 96, 98, 144, and 149. 

Notice that only the redeemed can sing the new song, because it is a song of victory. The followers of the beast who worship the dragon, cannot sing the new song, since they will be defeated along with the counterfeit trinity they worship and serve.

(Kim Riddlebarger)

Article 37: The Last Judgment 

(Belgic Confession)

Finally we believe, according to God's Word, that when the time appointed by the Lord is come (which is unknown to all creatures) and the number of the elect is complete, our Lord Jesus Christ will come from heaven, bodily and visibly, as he ascended, with great glory and majesty, to declare himself the judge of the living and the dead. He will burn this old world, in fire and flame, in order to cleanse it.

Then all human creatures will appear in person before the great judge-- men, women, and children, who have lived from the beginning until the end of the world.

They will be summoned there by the voice of the archangel and by the sound of the divine trumpet.

For all those who died before that time will be raised from the earth, their spirits being joined and united with their own bodies in which they lived. And as for those who are still alive, they will not die like the others but will be changed "in the twinkling of an eye" from "corruptible to incorruptible."

Then "the books" (that is, the consciences) will be opened, and the dead will be judged according to the things they did in the world, whether good or evil. Indeed, all people will give account of all the idle words they have spoken, which the world regards as only playing games. And then the secrets and hypocrisies of men will be publicly uncovered in the sight of all.