Revelation 4 and 5 describe the throne room of God in heaven and its activities. Prominent among them are the twenty-four elders:
Around the throne were twenty-four thrones, and on the thrones I say twenty-four elders sitting, clothed in white robes; and they had crowns of gold on their heads. . . . [T]he twenty-four elders fall down before Him who sits on the throne and worship Him who lives forever and ever, and cast their crowns before the throne, saying: "You are worthy, O Lord, to receive glory and honor and power; for You created all things, and by Your will they exist and were created" (Revelation 4:4, 10-11).
Some falsely teach that the twenty-four elders are taken from among saved mortals. This assumption is primarily based on a mistranslation of Revelation 5:8-10 in many versions, even the respected King James version. According to the Greek text, the last half of verse 9 and all of verse 10 should read:
For You were slain, and have redeemed them [the saints, not us] to God by Your blood out of every tribe and tongue and people and nation; and have made them [not us] kings and priests to our God; and they [not we] shall reign on the earth.
Notice the translation of these verses in the English Standard Version:
. . . for You were slain, and by Your blood You ransomed people for God from every tribe and language and people and nation, and You have made them a kingdom and priests to our God, and they shall reign on the earth.
From this correct text, we see that these "elders" are not changed mortals but powerful spirit beings who assist God at His throne in heaven. Verse 10 explicitly says that the resurrected saints will reign on earth! See Revelation 20:4 where this idea is repeated and expanded.
We know that the twenty-four elders are not redeemed human beings because no man except Jesus Christ (John 3:13) has ascended to heaven where God's throne is. All saved human beings—those who are Christ's true servants—will be given immortality at Christ's coming—when He returns to the earth to rule and reign (I Corinthians 15:22-23).
The twenty-four elders, then, are a part of the created heavenly host, that is, angels of high rank and honor. They are created spirit beings and have been given positions of responsibility in the government of God, through which He rules the universe. Revelation 5:8 says the elders each have a harp and golden bowls full of incense, symbolic of the prayers of the saints. From these symbols we can perhaps see a little of their function before God.
The harp is a musical instrument, and biblically, it was used a great deal in accompanying the Psalms and in the worship of God (see II Samuel 6:5; I Chronicles 15:16; 25:1, 3, 6; II Chronicles 5:11-14; Nehemiah 12:27; Psalm 33:2; 98:5; etc.). Similarly, the twenty-four elders are responsible for praising God in song, possibly in conducting vast choirs of angels (see Revelation 5:11-12).
The golden bowls full of incense representing the prayers of God's people hint at a second responsibility: that of carrying out God's answers to prayer. Perhaps, once God determines how a situation should be handled, He leaves its accomplishment in the hands of these trusted servants, who, Paul says, are "ministering spirits sent forth to minister for [serve for the sake of (ESV)] those who will inherit salvation" (Hebrews 1:14). Though this function is speculative, it is not inconsistent with the function of angels elsewhere in the Bible (see Daniel 9:20-23; 10:10-21).