As we come to Chapter 14 the corresponding letter is the letter "nun". This means faithfulness; soul; downfall and rising again. This certainly helps us again in the meaning of the chapter and applies to it. The 144,000 are indeed faithful.
Revelation 14:1-5 And I looked, and, lo, a Lamb stood on the mount Sion, and with him an hundred forty and four thousand, having his Father's name written in their foreheads. And I heard a voice from heaven, as the voice of many waters, and as the voice of a great thunder: and I heard the voice of harpers harping with their harps: And they sung as it were a new song before the throne, and before the four beasts, and the elders: and no man could learn that song but the hundred and forty and four thousand, which were redeemed from the earth. These are they which were not defiled with women; for they are virgins. These are they which follow the Lamb whithersoever he goeth. These were redeemed from among men, being the firstfruits unto G-d and to the Lamb. And in their mouth was found no guile: for they are without fault before the throne of G-d. (KJV)
In chapter 7 we met the 144,000.
Here we see the 144,000 Jewish believers with Y'shua on Mt. Zion. They have the name of G-d the Father written on their foreheads. They contrast those who take the "mark of the beast" in the previous chapter.
The voice like thunder we have seen before and it refers to coming judgment.
Now the burning question is "Where is THIS Mt. Zion?" Of course there is Mt. Zion is Jerusalem. However, this Mt. Zion appears to be in heaven.
Notice the following:
1) They are before the throne.
2) They are before the 4 beasts, which are always before the throne of G-d in heaven.
3) They are before the (24) elders, which we have already determined are the believers from the "church" age and they are also in heaven. They sing with the church before the throne of their redemption in heaven after being taken out of the tribulation.
144,000 have been redeemed from the earth. It appears that their earthly ministry is finished and they are now in heaven. Perhaps G-d allows them to be killed after they have finished their ministry of preaching the gospel to the world during the first 3 1/2 years of the tribulation period.
They also have a special song of praise that they alone sing. (a new song)
We learn that they are virgin men. The tribulation period is not a time to be settling down and raising a family. It will be a time to focus on surviving from day to day.
Y'shua said in Luke 23:29 For, behold, the days are coming, in the which they shall say, Blessed are the barren, and the wombs that never bare, and the paps which never gave suck. (KJV)
This may also refer to the fact that they have kept themselves spiritually pure in a time when the whole world is following after the ways of the devil.
This is alluded to in the phrase: Rev 14:4 "These are the ones who follow the Lamb wherever He goes." (NAS) They follow Y'shua and not the Anti-Messiah.
They were true to G-d and were "blameless" before him.